No start when cold, no log by computer

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WalkGood

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2005 Liberty Sport 4x4 3.7 engine 38,800 miles

When cold in the morning (close to 40* F), won't start (just cranks like a champ) or *might* start for 2 or 3 seconds then die, and just crank. No sputter, nothing. After awhile or when sun warms the air and car it will start. All other times, starts fine first thing.

Brought/towed to dealer many times they cannot duplicate problem, kept it overnight outside. Unfortunately when the problem happens, the next week is all warmer morning.

Last month had dealer do a tuneup (plugs, pcv, filter) and "complete emmission service" (machine cleaning of injectors and throttle body). No noticeable change in performance.

Cold morning yesterday (40*), no start. Dealer had it overnite but no problem this morning at 6:30AM. No logging of any errors by computer.

Crank sensor has been replaced (dec 2006) by dealer, had faulty crank trigger reference signal. They wiggled and checked this sensor.

Any one with any ideas?

Maybe needs new fuel filter? Why it wouldn't be changed with tuneup or the fuel injector service.....??? Seems filter change should be part of that service. Service guy should have thought of this dont you think?
 

tjkj2002

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Engine hard to start/no start when cold---

---Fuel not reaching injectors,check fuel filter,lines,and pump

---Defective engine coolant sensor

---Fuel injection system or engine control systems malfuntioning


Just some things to start looking at.As far as the fuel filter goes,Jeep deems it a lifetime filter,no need to change it,but I don't buy it I change mine every 30,000 miles.It's pricy since it also has the pressure regulator in it,and as far as I know the dealer is the only place to get it,last time I got one it was $150.Also the tank need to be dropped or rip the whole rear intior out and cut out the access panal above it out.
 

WalkGood

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Ya know, I suggested the coolant sensor as a possibility and the service guy dismissed that idea.

Anyone know how much that sensor costs and where EXACTLY it is located?
 

valvestem

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2005 Liberty Sport 4x4 3.7 engine 38,800 miles

When cold in the morning (close to 40* F), won't start (just cranks like a champ) or *might* start for 2 or 3 seconds then die, and just crank. No sputter, nothing. After awhile or when sun warms the air and car it will start. All other times, starts fine first thing.

Brought/towed to dealer many times they cannot duplicate problem, kept it overnight outside. Unfortunately when the problem happens, the next week is all warmer morning.

Last month had dealer do a tuneup (plugs, pcv, filter) and "complete emmission service" (machine cleaning of injectors and throttle body). No noticeable change in performance.

Cold morning yesterday (40*), no start. Dealer had it overnite but no problem this morning at 6:30AM. No logging of any errors by computer.

Crank sensor has been replaced (dec 2006) by dealer, had faulty crank trigger reference signal. They wiggled and checked this sensor.

Any one with any ideas?

Maybe needs new fuel filter? Why it wouldn't be changed with tuneup or the fuel injector service.....??? Seems filter change should be part of that service. Service guy should have thought of this dont you think?

I would take it back and have them check the idle control sensor.
 

WalkGood

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I would take it back and have them check the idle control sensor.

They say nothing is out of spec, no computer error codes stored. But I bet I'll be back there again when it gets cold here next week.
 

Pinks for slips

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Somthing in the ASD relay circut.
A good test would be to buy a cheap set of noid lights.
If it dont crank, plug a noid lamp into the injector plug, if it flashes suspect would be its not firing, (bad coil or voltage to coil).
If it dont flash ASD or Key module failed.
 

WalkGood

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Somthing in the ASD relay circut.
A good test would be to buy a cheap set of noid lights.
If it dont crank, plug a noid lamp into the injector plug, if it flashes suspect would be its not firing, (bad coil or voltage to coil).
If it dont flash ASD or Key module failed.

I've had older GM vehicles, not sure what is "ASD"?

And what are noid lights? Is that noid, sounds like Floyd? Or sounds like Know Eye Dee?

Note that the engine does crank, like a champ. Just won't start. no sputter no nothin.
 

WalkGood

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valvestem

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2005 Liberty Sport 4x4 3.7 engine 38,800 miles

When cold in the morning (close to 40* F), won't start (just cranks like a champ) or *might* start for 2 or 3 seconds then die, and just crank. No sputter, nothing. After awhile or when sun warms the air and car it will start. All other times, starts fine first thing.

Brought/towed to dealer many times they cannot duplicate problem, kept it overnight outside. Unfortunately when the problem happens, the next week is all warmer morning.

Last month had dealer do a tuneup (plugs, pcv, filter) and "complete emmission service" (machine cleaning of injectors and throttle body). No noticeable change in performance.

Cold morning yesterday (40*), no start. Dealer had it overnite but no problem this morning at 6:30AM. No logging of any errors by computer.

Crank sensor has been replaced (dec 2006) by dealer, had faulty crank trigger reference signal. They wiggled and checked this sensor.

Any one with any ideas?

Maybe needs new fuel filter? Why it wouldn't be changed with tuneup or the fuel injector service.....??? Seems filter change should be part of that service. Service guy should have thought of this dont you think?

I have been thinking about this for a couple days, and the issue may be a build up of carbon on the throttle plate that shuts off the little bit of air needed for a cold start. Hence no issue on warmer days. I had this problem on my old 4.0 YJ. Pop of the air cleaner assembly and look for the throttle plate assembly, squirt some carb cleaner and use a tooth brush to clean away the carbon. That's what the 5 Star dealer did to do away with my same issue. Luckily the service manager was standing there when I explained the issue, because the technician assigned was coming up with all the other possible causes already stated. (no offense intended to anyone).
 

WalkGood

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I have been thinking about this for a couple days, and the issue may be a build up of carbon on the throttle plate that shuts off the little bit of air needed for a cold start. Hence no issue on warmer days. I had this problem on my old 4.0 YJ. Pop of the air cleaner assembly and look for the throttle plate assembly, squirt some carb cleaner and use a tooth brush to clean away the carbon. That's what the 5 Star dealer did to do away with my same issue. Luckily the service manager was standing there when I explained the issue, because the technician assigned was coming up with all the other possible causes already stated. (no offense intended to anyone).

Well, the fuel injection and throttle body cleaning was supposed to take care of that possibility.
 

Pinks for slips

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Thanks for the info.

Any idea how much a SCAN tool would cost that can be helpful with my problem?

Well,,a scan tool wont help You at the moment..If the dealer could not pull up any codes You wont either.
If the ASD system/relay is enabled/disabled codes will not be set.

Thats where the noid lite comes in..You can plug it in and spin the engine over and watch to see if it flashes..If it does'nt,, this is where You start to find the problem.
For a few bucks its a great tool and they work on a lot of foriegn and domestic cars & trucks...

Your ECM sends a signal to fire the injector (noid lite flashes).
Your ECM Sends a signal to fire the coil the same voltage that drives the injector drives the coil(S)

The ASD Relay can shut down all of this!

Its the best place to start trouble shooting Your problem.
 

WalkGood

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Well,,a scan tool wont help You at the moment..If the dealer could not pull up any codes You wont either.
If the ASD system/relay is enabled/disabled codes will not be set.

Nah, not to look for codes but to see what info is available WHILE trying to start like what is the coolant sensor telling the ECM; is there a signal being received from the crank trigger; etc etc Stuff like that.
 

Atrus

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autotap.com is a decent price if you have a laptop or a PDA. Still going to run you $350 or so.

Enhanced parameters will tell you everything - you just need to have good automotive knowledge to compile an analysis based on the data. Also lets you log and import into excel, so you can check several parameters while driving and see the whole picture. It really is a great little tool.

Nice thing is it'll clear codes on any OBD-II vehicle, and it'll do enhanced parameters on the vehicle line of your choice. I have one for all GM vehicles as 99% of the cars in my family are GM. I am the odd duck other than my brother's Sonata.
 

Pinks for slips

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Nah, not to look for codes but to see what info is available WHILE trying to start like what is the coolant sensor telling the ECM; is there a signal being received from the crank trigger; etc etc Stuff like that.

If the ASD relay is active ..It kills the voltage to the crank sensor..You won't see much. Also it shuts down the ECM/PCM.

Let Me get a run down from Alldata and post it.
 

WalkGood

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If the ASD relay is active ..It kills the voltage to the crank sensor..You won't see much. Also it shuts down the ECM/PCM.

Let Me get a run down from Alldata and post it.

Thanks for checking Alldata.

I don't have any knowledge of the ASD and what it affects.... but why would the starter be allowed to crank at all if the ASD was in shutdown mode?

What is the "normal" reasons that the ASD would shutdown? Like if the car flipped over?
 

valvestem

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Well, the fuel injection and throttle body cleaning was supposed to take care of that possibility.

Well, going by the symptoms you describe, that might warrant you just checking the area I mentioned. I have already been through what you describe, and the fix was as I already stated. Goodluck.
 

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page 1 ....

Description and Operation

PCM OUTPUT
The 5-pin, 12-volt , Automatic Shutdown (ASD) relay is located in the Power Distribution Center (PDC). Refer to label on PDC cover for relay location.

ASD SENSE - PCM INPUT
A 12 volt signal at this input indicates to the PCM that the ASD has been activated. The relay is used to connect the oxygen sensor heater elements, oxygen sensor heater relay, ignition coil and fuel injectors to 12 volt + power supply.

This input is used only to sense that the ASD relay is energized. If the Powertrain Control Module (PCM) does not see 12 volts at this input when the ASD should be activated, it will set a Diagnostic Trouble Code (DTC).

PCM OUTPUT
The ASD relay supplies battery voltage (12+ volts ) to the fuel injectors and ignition coil(s). With certain emissions packages it also supplies 12-volts to the oxygen sensor heating elements and the oxygen sensor heater relay.

The ground circuit for the coil within the ASD relay is controlled by the Powertrain Control Module (PCM). The PCM operates the ASD relay by switching its ground circuit on and off.

The ASD relay will be shut-down, meaning the 12-volt power supply to the ASD relay will be de-activated by the PCM if the ignition key is left in the ON position. This is if the engine has not been running for approximately 1.8 seconds .
 

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The BCM is enclosed in a molded plastic housing with two integral external connectors that connect it to the vehicle electrical system through two take outs with connectors from the instrument panel wire harness. The BCM also has an integral interface connector that joins it through a connector receptacle that is integral to the JB housing to the circuitry within the JB. This connector is referred to as the JB-BCM connector. The combined BCM and JB are sometimes referred to as the Junction Block Module (JBM).

The BCM utilizes integrated circuitry and information carried on the Programmable Communications Interface (PCI) data bus along with many hard wired inputs to monitor numerous sensor and switch inputs throughout the vehicle. In response to those inputs, the internal circuitry and programming of the BCM allow it to control and integrate many electronic functions and features of the vehicle through both hard wired outputs and the transmission of electronic message outputs to other electronic modules in the vehicle over the PCI data bus.

The electronic functions and features that the BCM supports or controls include the following:


A/C Select Switch Status - The BCM monitors an input from, and transmits the status of the A/C switch in the heater-A/C control
Audio System Cabin Equalization - The BCM stores the cabin equalization curves for numerous optional speaker architectures for use by the radio The equalization curve information allows the radio to optimize sound output for the unique combination of cabin and speaker architecture found within the vehicle The BCM provides this information when requested by the radio over the PCI data bus
Cargo Lamp Disable - The BCM monitors an input from the cargo lamp switch to provide an interior lighting disable feature
Chimes - The chime tone transducer is located on the ElectroMechanical Instrument Cluster (EMIC) circuit board, but the EMIC goes to sleep with the ignition switch in the Off position The BCM provides a wake-up output to the EMIC based upon inputs from the key-in ignition switch or the exterior lighting switch, then sends electronic chime request messages to the EMIC for the headlamps-on warning and key-in ignition warning
Door Lock Inhibit - The BCM monitors the key-in ignition switch and the driver side front door ajar switch to provide a door lock inhibit feature
Electronic Pinion Factor - On vehicles without the optional Antilock Brake System (ABS) the BCM provides a source voltage to the rear wheel speed sensor and monitors a returned vehicle speed signal input. The BCM is able to use the vehicle speed signal input to accurately calculate vehicle speed and distance information by applying an electronic pinion factor. This factor is based upon either a pre-programmed tire size or a Tire Revolutions per Mile (TIRE REV/MILE) value that compensates for multiple optional axle ratios and tire diameters. The correct electronic pinion factor must be programmed into the BCM using a diagnostic scan tool in order for the vehicle speed and distance information to be accurate. The BCM then transmits the correct vehicle speed information over the PCI data bus for use by the EMIC for control of the speedometer and odometer.
Enhanced Accident Response Support - The BCM monitors an input from the Airbag Control Module (ACM) and, five seconds after a front or side airbag deployment will unlock all doors by activating the power unlock output if the power lock switch input remains inactive for two seconds . The BCM also turns on the interior lighting after an airbag deployment event, five seconds after the vehicle speed is zero. The interior lighting remains illuminated until the ignition switch is turned to the Off position, at which time the interior lighting returns to normal operation and control. These Enhanced Accident Response System (EARS) features are each dependent upon a functional vehicle electrical system following the vehicle impact event.
Exterior Lamp Load Shedding - The BCM provides a battery saver feature which will automatically turn off exterior lamps that remain on after a timed interval.
Exterior Lamp Status - The BCM monitors the status of the park lamp, low beam, high beam or Daytime Running Lamp (DRL - Canada only), front fog lamp (optional), and rear fog lamp (in required markets only) relays.
Exterior Lighting Control - The BCM provides exterior lamp control for standard head and park lamps, as well as Daytime Running Lamps (DRL - Canada only), front fog lamps (optional), and rear fog lamps (in required markets only). This includes support for features including optical horn (also known as flash-to-pass) and headlamp time delay.
Flip-Up Glass Control - The BCM monitors inputs from the tailgate cylinder lock switch, the tail-gate handle switch, the Remote Keyless Entry (RKE) system and the rear wiper switch to provide control for the rear flip-up glass actuator.
Fog Lamp Control - The BCM provides fog lamp control for front fog lamps (optional), and rear fog lamps (in required markets only).
Front Wiper System Status - The BCM monitors the status of the front wiper motor park switch.
Fuel Economy and Distance to Empty Calculations - The BCM calculates and transmits the fuel ECOnomy (ECO) and Distance To Empty (DTE) data.
Headlamp Time Delay - The BCM provides a headlamp time delay feature with the ignition switch in the Off position.
Heated Rear Glass Control - The BCM provides control and timer functions for the heated rear glass feature and transmits the system status.
Ignition On/Off Timer - The BCM monitors and transmits the elapsed ignition On timer data and monitors the ignition Off time.
Ignition Switch Position Status - The BCM monitors and transmits the status of the ignition switch.
Instrument Panel Dimming - The BCM monitors and transmits the selected illumination intensity level of the panel lamps dimmer switch.
Interior Lamp Load Shedding - The BCM provides a battery saver feature which will automatically turn off all interior lamps that remain on after a timed interval.
 

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Interior Lighting Control - The BCM monitors inputs from the interior lighting switch, the door ajar switches, the flip-up glass ajar switch, the tail-gate ajar switch, the cargo lamp switch, the reading lamp switches, and the RKE system to provide courtesy lamp control. This includes support for timed illuminated entry with theater-style fade-to-off and courtesy illumination defeat features.
Intermittent Wipe and Front Wiper System Control - The BCM monitors inputs from the front wiper and washer switch and the front wiper motor park switch to provide front wiper system control through the wiper on/off and high/low relays. This includes support for adjustable intermittent wipe, mist wipe (also known as pulse wipe), and wipe-after-wash features.
Key-In-Ignition Switch Status - The BCM monitors and transmits the status of the key-in-ignition switch.
Panic Mode - The BCM provides support for the RKE system panic mode feature.
Parade Mode - The BCM provides a parade mode (also known as funeral mode) that allows the interior Vacuum Fluorescent Displays (VFD) to be illuminated at full intensity while driving in daylight with the exterior lamps On.
Power Locks - The BCM monitors inputs from the power lock switches and the RKE system to provide control of the power lock motors through outputs to the lock, unlock, and driver unlock relays. This includes support for rolling door locks (also known as automatic door locks) and a door lock inhibit mode.
Programmable Features - The BCM provides support for several standard and optional programmable features, including: rolling door locks, headlamp time delay interval, RKE driver-door-only or unlock-all-doors, RKE optical chirp, and RKE audible chirp.
Remote Keyless Entry - The BCM provides support for the RKE system features, including support for the RKE Lock, Unlock (with optional driver-door-only unlock, and unlock-all-doors), rear flip-up glass control, Panic, audible chirp, optical chirp, and illuminated entry modes.
Rolling Door Locks - The BCM provides support for the power lock system rolling door locks feature (also known as automatic door locks).
Tailgate and Flip-Up Glass Ajar Status - The BCM monitors and transmits the status of the tail-gate and rear flip-up glass ajar switches.
Remote Radio Switch Interface - The BCM monitors and transmits the status of the optional remote radio switches.
Self-Diagnostics - The BCM provides support for diagnostics through communication with a diagnostic scan tool over the PCI data bus network. Each analog and digital input can be verified, and each output can be actuated through the use of this diagnostic protocol. The BCM also stores Diagnostic Trouble Codes (DTCs) to assist in the troubleshooting of this unit.
Vacuum Fluorescent Display Synchronization - The BCM transmits panel lamp intensity data which allows modules with Vacuum Fluorescent Displays (VFD) to coordinate their illumination intensity.
Vehicle Theft Security System - The BCM monitors inputs from the door ajar switches, the tail-gate ajar switch, the flip-up glass ajar switch, the hood ajar switch (in required markets only), and the RKE system to control the features of the optional Vehicle Theft Security System (VTSS).
Hard wired circuitry connects the BCM to the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the BCM through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.
Many of the electronic features in the vehicle controlled or supported by the BCM are programmable using a customer programming procedure or a diagnostic scan tool. In addition, the BCM software is Flash compatible, which means it can be reprogrammed using Flash reprogramming procedures. However, if any of the BCM hardware is damaged or faulty, the entire BCM unit must be replaced.

The microprocessor-based Body Control Module (BCM) monitors many hard wired switch and sensor inputs as well as those resources it shares with other electronic modules in the vehicle through its communication over the Programmable Communications Interface (PCI) data bus network. The internal programming and all of these inputs allow the BCM microprocessor to determine the tasks it needs to perform and their priorities, as well as both the standard and optional features that it should provide. The BCM programming then performs those tasks and provides those features through both PCI data bus communication with other electronic modules and through hard wired outputs through a number of driver circuits, relays, and actuators. These outputs allow the BCM the ability to control numerous accessory systems in the vehicle.

The BCM operates on battery and ignition voltage inputs received through several fuses in the Junction Block (JB) on a non-switched fused B(+) circuit, through another fuse in the JB on a fused ignition switch output (run-start) circuit, and through a third fuse in the JB on a fused ignition switch output (run-acc) circuit. This arrangement allows the BCM to provide some features regardless of the ignition switch position, while other features will operate only with the ignition switch in the On, Start, and/or Accessory positions. All of the battery voltage circuits are connected to the BCM through the JB/BCM connector.

The BCM receives ground through five separate circuits. Three of these circuits are connected to the BCM through a connector of the instrument panel wire harness on three separate ground circuits, while the other two circuits are connected to the BCM through the JB/BCM connector. Each of these circuits receives a path to ground through the instrument panel wire harness with an eyelet terminal connector that is secured by a nut to a ground stud on the driver side instrument panel end bracket near the JB.

The BCM monitors its own internal circuitry as well as many of its input and output circuits, and will store a Diagnostic Trouble Code (DTC) in electronic memory for any failure it detects. These DTCs can be retrieved and diagnosed using a diagnostic scan tool.

INPUT AND OUTPUT CIRCUITS

HARD WIRED INPUTS
The hard wired inputs to the BCM include the following:


A/C on/off control
BCM Hash enable
Door lock switch mux
Driver door ajar switch sense
Flip-up glass ajar switch sense
Flip-up glass release switch sense
Front fog lamp switch sense
Front wiper park switch sense
Front wiper switch mux
Fused B(+)
Fused ignition switch output (run-acc)
Fused ignition switch output (run-start)
Headlamp switch mux
High beam switch sense
Hood ajar switch sense - with VTSS - in markets where required only
Key-in ignition switch sense
Left rear door ajar switch sense
Lightbar switch sense - Renegade with light bar only
Panel lamps dimmer switch mux
Passenger front door ajar switch sense
Radio control mux - with remote radio switches only
Rear courtesy lamp control
Rear window defogger control
Rear wiper intermittent driver
Rear wiper on driver
RHD input - connected to ground on right-hand drive models only
Right rear door ajar switch sense
Tailgate ajar switch sense
Washer pump driver
Vehicle speed signal
HARD WIRED OUTPUTS
The hard wired outputs of the BCM include the following:


Accessory delay relay control - power sunroof only
Courtesy lamp driver
Courtesy lamp load shed
Door lock relay control
Door unlock relay control
Driver door unlock relay control
Flip-up glass release motor driver
Front fog lamp relay control
Front wiper high/low relay control
Front wiper on/off relay control
Fused B(+) - lock, unlock and driver unlock relay feed
Hazard lamp control
High beam relay control
Horn relay control
Instrument cluster wake up signal
Low beam relay control
Park lamp relay control
Rear fog lamp relay control - with rear fog lamps in markets where required only
Rear window defogger relay control
Tailgate lock driver
Tailgate unlock driver
Vehicle speed output
Vehicle speed sensor supply - except with Antilock Brake System (ABS)
VTSS indicator driver - with VTSS only.
GROUNDS
The BCM receives ground through five separate circuits, and also supplies a clean ground path to several switches through the following hard wired circuits:


Door lock switch ground
Multifunction switch ground
Radio control mux return
Tailgate switch ground
COMMUNICATION
The BCM has the following communication circuits:


PCI bus
 

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