Electrical Problems P1491 and P1682

[blacknewt]

Greetings, I was wondering if I could get some help. Today I noticed that my check engine light came on, I was getting error code P1491 (Cooling Fan Relay Control Circuit). I tested the fuse and it tested good so i assumed it was a bad relay and ordered it. Then a few hours after my battery light came on. I checked the codes again and got P1682 (Charging System Voltage Too Low). I tested the battery and got 12.4V engine off and 11V engine on. This leads me to believe it is the charging system but got me thinking if it could possibly be the PCM. Any help would be greatly appreciated.

 

[kb0nly]

How old is the battery?? Just curious because thats the first place to start when it comes to an electrical problem like that.

However, you said its 11v with the engine running so that leads me to believe you might also have an alternator problem.

The cooling fan circuit problem could be related to the low voltage problem, just a random code getting popped up because of the sagging voltage.

What model year is your KJ??

And i see this is your first post.. Welcome!!

 

[blacknewt]

My jeep is a 2003 limited. The battery is labeled Jun 07 if I remember correctly.

 

[HoosierJeeper]

However, you said its 11v with the engine running so that leads me to believe you might also have an alternator problem.

Thinking that as well, (welcome) BTW...

 

[blacknewt]

Thanks for the replies. Are there any other tests that I might be able to perform to be a bit more certain? Also, if it is the alternator are there any recommendations on what to get?

 

[tjkj2002]

You can not 100% rule it a bad alternator or a bad PCM until you connect a DRBIII(or StarScan) to the KJ.

As per every KJ FSM...............

To perform a complete test of the charging system,
refer to the appropriate Powertrain Diagnostic Procedures
service manual and the DRB scan tool.

 

[LibertyTC]

Sounds like you have a VOM for getting your voltage. Your battery is at 12.4 (low) because the alt is not currently charging, applying a drain. Eleven volts running tells the story, it should be 14.7 aprox.
You could try charging up the battery, with negative cable removed, and make sure one of the cells is not pooched. a fully charged good battery should hold about 13.2+ volts 20 minutes after taking the charger off.
Pointing to your alt, but bad batteries do strange things to KJ too.

 

[ShadowedXistence]

if it does turn out to be the alternator, i do believe the renegade one has a higher amp rating... anyone correct me if im wrong here

 

[LibertyTC]

yes 160 amp

The renegade does have the larger capacity alt, off the top of my head it is 160 amp. Wonder if a local alt repair shop could test and replace the faulty component (regulator) inside ? Hate to ask how much dealer wants for one..

 

[blacknewt]

I was actually looking at Advance Auto and they have a 160A for $121 with a 32 core charge (Link). Any ideas if it is worth it? It is probably the only place close by that has one that does not involve the dealership. Plus this is my DD and I have to get it working soon.

 

[kb0nly]

If your not running a Renny now then it doesn't matter to buy the larger alternator. The computer controls the output, so if your computer isn't programmed for the larger alternator then it won't do you any good to get it. Get the stock size!

I know this sounds stupid, but thats how it is on the KJ. Also, for the cost of having a stealership diagnose the system you could swap the alternator and keep your receipt for a return if that doesn't fix it!

Here is what i suggest, go get new alternator, pay core charge and keep receipt, go home and swap the alternator, if it fixes the problem bring your old one and receipt back and get core charge refund. If it doesn't fix the problem bring the new one back and get full refund. I haven't run into a parts place yet that wouldn't take it back if i told them i didn't end up needing it.

 

[kb0nly]

I was actually looking at Advance Auto and they have a 160A for $121 with a 32 core charge (Link). Any ideas if it is worth it? It is probably the only place close by that has one that does not involve the dealership. Plus this is my DD and I have to get it working soon.

Looking at Advance its only a couple dollars difference in pricing between the stock 132 and the 160. So its your choice, but just realize you won't get 160 amps out of it on a non-renegade KJ.

 

[blacknewt]

Thanks everyone for the advice. I will pick up the alternator tomorrow.

 

[LibertyTC]

Results

Please let us know what happens...!!
Hopefully replacing the alt restores the charging problem!
Look forward to your installation results!

 

[ShadowedXistence]

Quick question... what is the purpose of the Renegade having the larger output alternator... the only extra I can think of is the roof lights, which I couldn't see drawing that much extra?

 

[LibertyTC]

Extra juice !

Reny's with light bar, I guess they figured the extra draw needed extra amps.
Too bad they could not figure out that an 800CCA battery should be standard issue equipment, to go with them. poke.gif

 

[blacknewt]

Now running at 14V with a new alternator. Hopefully that also takes care of my P1491. Thanks again everyone for your help.

 

[frankblack]

I have encountered the same problem

about three days ago my jeep threw code P1491 (radiator fan relay control circuit) out then the engine light turned off once I parked for awhile. Once I started my jeep up again after several minutes the code returned. Day two.. code P1491 was accompanied by a new code P1682 (charging system voltage low). once the P1682 showed up my jeep started to idle erratically and then would not idle at all.

trouble shooting the code I decided to work on the battery power related issue first. I replaced the battery and alternator. When I tried to start my jeep a big cloud of blue came out the tail pipe and my jeep would only crank without turning over. the more I cranked it over the motor started to make a clunking sound. So I stopped and now seek help from the experts on this forum..as all the quick fix's have not worked:3681700093_1f8b56e8

 

[LibertyTC]

Welcome to the forum fellow BC'er.
Clunking is really bad news, so is blue smoke out the tail pipe.
Does the clunking sound like it is coming from the top end?
First thing to do is pull both valve covers and have a good look in there.
How long did the Jeep sit for without starting?
The 3.7 unfortunately can fling a rocker, and you need to inspect the valve train now.
Post a few pics if you are not sure what to look for, of both sides.

 

[frankblack]

the knocking sound almost sounded like if the timing was off. I tried starting it again a few hours later and it still would not turn over although no smoke or clunking sounds. what I'm wondering is... could the crank and camshaft somehow get out of alignment when I took off the fan belt while changing the alternator.. I'm not sure even if that makes sense..lol