URGENT HELP!: Fuse 26 keeps blowing...

[bigman]

Fuse number 26 will blow upon key in the run postion. It is the injector fuse. Thus, the jeep will not start. Im at wits end on this thing. So far I have checked the following:

Supply side of fuse wire (OR/GR) to PCM input connector (OR/GR). Checked for continuity, was good. Checked it to ground for a short, passed.

Output side of PCM connector signal injecotor wire to each respective injector. All passed continuity and ground for short.

Checked all injectors plugs (injector side) for short to ground. Passed.

After injectors plugs pulled, checked for fuse blowage (?) FAILED! Indicating injectors are good.

Pull the ASD relay and fuse will not blow. I have found information on the C102 connector but have had no luck finding the location.

Some other things I thought were odd. There is continuity from the power plate of the PDC to ground! I pulled ALL the fuses and one by one checked them. The Ignition/START is the culprit. Pink/Black wire is grounded out.

26 fuse will still blow with Ignition/Start fuse removed.

I have pulled the o2 sensor relay and fuse 26 still blows.

Im thinking it is something with the C102 connector or the wiring to/from it. Fuse 26 gets power from the ASD relay.

Any help would be great, Im walking to work until its fixed, and winter is fast approaching!!!

 

[Billwill]

What year/model is your Jeep? Do you have a circuit diagram?
I only have circuit diagrams for 2002 KJs....on the "Locations" it states C102 is for RHD only but there are lots of mistakes in the diagrams.

 

[bigman]

What year/model is your Jeep? Do you have a circuit diagram?
I only have circuit diagrams for 2002 KJs....on the "Locations" it states C102 is for RHD only but there are lots of mistakes in the diagrams.

aparantley my sig did not work.

Jeep is a 2003. 3.7

edit that, it did work, just did not update to the first post!

I have some half-ass diagrams. Bought a manual from the zone, does not show detailed engine electrical, just starting/charging systems.

I will try removing the power wire from the ASD relay to the 26 fuse. Temporarely run from battery to fuse, and see if it blows the fuse.

 

[bigman]

I have these along with the haynes manual. You may have to sign in/have an account to view. I am looking at the Fuel Ignition Systems 1 and 6.

http://www.autozone.com/autozone/re...epairGuideContent.jsp?pageId=0996b43f802d86c1

 

[bigman]

UPDATE: I cut the wire (GR/OR) that comes from the ASD power to the supply side of the #26 fuse. I then ran a wire from battery + to the supply of the fuse. I installed a fuse and it blew instantly. This tells me that the ASD relay/fuse and all other circuitry running off from it is intact and fine.

So, does this mean the PCM is fried...? As posted above I have checked all wires to and from the PCM associated with the injectors.

Anythoughts on this? is my logic and elimination of things sound proper..?

 

[Billwill]

OK my 2002/3 circuit diagrams are the same as yours. I do not quite follow you when you said you cut the wire from ASD power to supply side of fuse #26 and then connected a wire direct to the fuse and it blew? That would indicate to me that there is indeed a problem going from pin 37 on Fuse #26 to either the injectors or the PCM.
I have a concern that somewhere the OR/DG wire is going to ground or is merged with some other wire....I have had plenty of these problems.
In other words there is a problem with the output of Fuse #26 where it goes through connector C103 to the fuel injectors or with Pin 12 on C3 on the PCM.
You need to cut the OR/DG wire going to the PCM right at Fuse #26 pin 37 and see if fuse still blows....this should isolate the PCM at pin 12 on C3.
Then re-connect that wire and cut the wire going to C103 again right at the Fuse #26 pin 37 connector and see if the fuse blows....no good disconnecting C103 as the OR/DG wire could be going to ground somewhere....this isolates the injectors.
I have had about six problems where I had to cut wires off at both ends and tape them aside and run a complete new wire from point to point. This is because the wires, when isolated, still showed some form of conductivity to ground or to somewhere else. My Jeep had been involved in a Front/Right crash and I believe the harness which runs through that area had been damaged.

 

[bigman]

I cut the DG/OR from fuse #26. This come from the ASD relay (on paper) it really dont go right to the relay. I ran a temp. wire from battery + to DG/OR (supply power to fuse).

This test eliminates any possibility that the DG/OR from ASD relay has a problem anywhere.

My next test is to unplug the connector at the PCM that has the OR/DG wire. Still leaving the temp. wire connected. If it still blows, there would be a short to ground in the OR/DG wire. Then I would just run a new wire. If it does not blow, the OR/DG wire is good. I will then unplugg the out connector at PCM which has the signal wires out to the injectors. If fuse does not blow, I will run 6 new signal wires.

Here is a pic of the temp wiring I did.

You must be registered for see images

 

[bigman]

Also, can you explain/post a pic of the c103, pin 12, c3 stuff. I am totally lost on this terminalogy.

 

[bigman]

UPDATE: Ok, so I went out. Unplugged the connector closest to the windsheild on the PCM, this has the OR/GR wire from fuse 26. Installed fuse, did NOT blow. Unplugged middle connector (contains signal wires to injectors) plugged IN connector with OR/GR and the fuse blew. The PCM has to be bad. I can get one for $50. This theory sound correct?

 

[Aaron2345]

Can't help but really kind of excited to see the outcome. I know wiring and seems like you did all you can do . I would personally buy the new pcm as of now

 

[bigman]

You and me both! I used the test light I got in a remote start kit

I tested were the fuse goes in. The OR/GR was showing a green light, indicating ground. Unplug the PCM side connector and no green light. I check the pin on the PCM, it showed ground. There were other pins that grounded out, any one have a detail pinout on the PCM?

At this point Im worried that something else is causing the PCM to short out, I dont want to spend the money and blow another PCM!

 

[bigman]

UPDATE: COMPLETE LOSS AT THIS POINT!!!

I bought the computer- $55. Install and it blows the fuse. I ONLY plugged in the 3rd connector. If I put my probe on the OR/GR wire at fuse #26, plug in the connector at PCM it grounds out. Unplug the connector, check OR/GR at #26 to ground, nothing. Check pin 12 to ground nothing! What the hell is going on here!!!

 

[bigman]

I can not find where the 2nd OR/GR wire goes to. There are (2) at the fuse. I checked all wires out of the loom and there is only (1)! At pin 12.

 

[bigman]

http://dto.vftis.com/mopar/main.asp

 

[bigman]

UPDATE: I checked with my test light the connectors that I now think are C1,C2,C3.

C3 - 26,25,24,23,20,19,14,11,10,5,4,3,1 are all grounded out.

C2 - 23,10 are gounded out

C1 - 32,31,13,12,6,2 are grounded out.

I think there is a major grounding issue somewhere. But no other fuses are blown.

 

[bigman]

So I have found that one of the (2) OR/GR wires coming from fuse #26 goes right to pin 12 on C3. I cut this wire. I put my tester lead on the now stripped wire. I put the other lead on pin 12 of C3. It has connection. I test the stripped side and ground, nothing. I test the pin side to ground, nothing. If I plug C3 into the PCM and put the lead on the stripped end of wire and the other lead to ground, it shows a connection! WTF!

So, I unplugg the C3 from the PCM. I test pin 12 to every other pin in C3. NOTHING!

I know its possible, but do you think I got a bad PCM...!?!?!??!!

 

[bigman]

I checked the pin outs on the PCM. Both PCMs show a connection between C3 25 and 12. We know that 12 runs to the ASD and 25 runs to the generator source. We also know that 25 is grounded out.

 

[Billwill]

UPDATE: I checked with my test light the connectors that I now think are C1,C2,C3.

C3 - 26,25,24,23,20,19,14,11,10,5,4,3,1 are all grounded out.

C2 - 23,10 are gounded out

C1 - 32,31,13,12,6,2 are grounded out.

I think there is a major grounding issue somewhere. But no other fuses are blown.

C3 is a light gray 32 pin plug.
There is no way that all the pins that you have measured...26---1 should go to ground! I think you need to use a proper Ohm meter (digital) to do these measurements....not a test light.

i will attach the pin-outs for the PCM for you later.

 

[Billwill]

I can not find where the 2nd OR/GR wire goes to. There are (2) at the fuse. I checked all wires out of the loom and there is only (1)! At pin 12.

The second Orange/Dark Green wire goes into pin 1 of C103 and then to all the injectors via a common splice S178.
The other ends of the injectors go to the PCM where ground will be switched to them.

 

[Billwill]

Here are some attachments: x marks the spots where I think you should cut wires for diagnosis. I found with my wiring problems that the wire tends to "melt" to ground or into another random wire next to it in the harness. You need to isolate a failing wire by cutting it at both end(multiple ends if there is a splice going off somewhere) and laying a new wire. Cut the wires until the fuse no longer blows then you will know which circuit it is on.
You need to get a proper digital multimeter to fix this problem...I do not think a test probe is accurate enough. Then you can test your theory of pin 12 and pin 25 on the PCM being joined together and going to ground.:disgust: