Charging Problem On Gen IV

[RPM9000]

Last night I stopped and gassed up and when I started the engine up the Check Engine Light was on. I didn't notice it before I stopped for gas. I didn't have time to check it out last night so today I took it out test drive and it ran fine. The light was still on then I noticed that the volt meter guage was reading about 11 volts. So I turned off the AC and radio and headed for home. When I got home I put my voltmeter across the battery and started the engine and it read about 11.5 volts no matter what the rpm's. Has anyone had this problem with their Gen IV? It looks like the original battery. The car has 11900 miles on it. I am hoping it is the battery but I think it is most likely the alternator. Any ideas??

[01sapphirebob]

I'd start with a new battery. Die Hard Platinum.

[Wiretech]

Its the alternator, with the engine running you should a reading of 13.5v and with engine off 12.2v and the reason why you are reading 11.5 v is the battery is low and not charging.

[Steve M]

Seems to point to the alternator not charging properly as mentioned...might need replaced.

Do you keep the car on a tender when not in use?

[RPM9000]

No I don't because I drive it usually once a week. I figured it was the alternator but it was just wishful thinking that it could be the battery.
Seems to point to the alternator not charging properly as mentioned...might need replaced.

Do you keep the car on a tender when not in use?

[Steve M]

These cars seem to drain batteries like it is their job, so it might have contributed to the issue...an alternator isn't gonna be happy if it has to keep charging a low battery every time it is run.

It might be a stretch, but something to think about.

[FLATOUT]

Paul I did keep your car on a battery tender when I owned it.

[Steve-Indy]

If battery is original, it is likely 7 years old. You need a new battery.

Effect of heat on batteries well known. Houston is hot. You need a new battery.

Testing alternator is a good idea. You need a new battery.

Get a battery tender to go with your new battery.

[IndyRon]

No I don't because I drive it usually once a week. I figured it was the alternator but it was just wishful thinking that it could be the battery.

You also have an UD pulley on the car using the stock length OEM serpentine belt. Most folks haven't had a problem with this setup, but if the belt is relatively old and glazed, it could be slipping in conjunction with increased load from the A/C compressor, less belt wrap on the Crank pulley plus the fact that the tensioner is almost bottomed out. I ended up switching to a slightly shorter belt on mine for peace of mind. Let me know if you rule out the others and I'll dig up that part number for you for the shorter belt. It's about 1" shorter if I remember correctly.

[FLATOUT]

Ron I'd love that part number for my gen V as well. Belts are the same and I have been meaning to switch to a smaller one with my under drive pulley.

Andy



You also have an UD pulley on the car using the stock length OEM serpentine belt. Most folks haven't had a problem with this setup, but if the belt is relatively old and glazed, it could be slipping in conjunction with increased load from the A/C compressor, less belt wrap on the Crank pulley plus the fact that the tensioner is almost bottomed out. I ended up switching to a slightly shorter belt on mine for peace of mind. Let me know if you rule out the others and I'll dig up that part number for you for the shorter belt. It's about 1" shorter if I remember correctly.

[scdazet]

You also have an UD pulley on the car using the stock length OEM serpentine belt. Most folks haven't had a problem with this setup, but if the belt is relatively old and glazed, it could be slipping in conjunction with increased load from the A/C compressor, less belt wrap on the Crank pulley plus the fact that the tensioner is almost bottomed out. I ended up switching to a slightly shorter belt on mine for peace of mind. Let me know if you rule out the others and I'll dig up that part number for you for the shorter belt. It's about 1" shorter if I remember correctly.

Ditto on the belt number part request. About to install a UD pulley on Gen IV.

[Steve-Indy]

Foul...no one said underdrive pulley in original post !! :)

I would still recommend a new battery.

[Bluecoupe]

If the voltage on the battery did not change with the motor running, it is the alternator, probably the voltage regulator inside the alt. if you put a new battery in the car, the same problem will occur.

[RPM9000]

Ok guys here is what I did today. I removed the alternator and took it to two different parts stores and it checked out good at both places. The battery checks good also, so I put it back together and still no charge. Check engine light still on and volt guage still showing 12 volts.

[Steve M]

Check the wiring harness and make sure you don't have any melted or broken wires somewhere along the run to the alternator.

[Shooter]

Ok guys here is what I did today. I removed the alternator and took it to two different parts stores and it checked out good at both places. The battery checks good also, so I put it back together and still no charge. Check engine light still on and volt guage still showing 12 volts.

Did you clear the check engine light before hooking everything back up again.? Unless cleared, it can stay on even after fixing a problem.

[Steve M]

Did you clear the check engine light before hooking everything back up again.? Unless cleared, it can stay on even after fixing a problem.

If the gauge is showing 12 volts, the problem isn't fixed.

[RPM9000]

No I didn't clear the light but the alternator is still not putting out anything. I'm going to call Tomball Dodge and talk to Morgan the viper tech and see if he has any ideas. Otherwise I will have to borrow a trailer and haul it to him. I don't think I could make the drive on a fully charged battery.(65 mile trip)

[Austin]

If battery is original, it is likely 7 years old. You need a new battery.

Effect of heat on batteries well known. Houston is hot. You need a new battery.

Testing alternator is a good idea. You need a new battery.

Get a battery tender to go with your new battery.



So basically you're saying that its the alternator?





































Kidding.

[Steve-Indy]

Hi, Austin.

Glad alternator was tested. I wonder if it is the plug or wiring from the unit that is bad as I have heard of that in a couple of instances where work was recently done on the car...OR, it's the alternator itself as suggested.

In any event I WOULD REPLACE THE BATTERY as well if it is indeed the original. :)

[AaronFL]

On my Gen 2, I had a similar issue. After replacing the battery, alternator, and BTS I had the same problem. It ended up being the voltage regulator circuit in the PCM was faulty. A new PCM fixed the problem.

[FLATOUT]

On my Gen 2, I had a similar issue. After replacing the battery, alternator, and BTS I had the same problem. It ended up being the voltage regulator circuit in the PCM was faulty. A new PCM fixed the problem.

Car has a Mopar ECU in it. I either bought it new from Tomball or ACRucrazy I can't remember.

[mjorgensen]

What were the codes for the CEL? You could have a dead short in an o2 harness.

[RPM9000]

I found out today that my problem was a bad Mopar pcm. I installed the factory pcm back in the car and the CEL went off and the alternator is now charging. I want to give Morgan Viper Tech. at Tomball Dodge a big thanks for helping me over the phone.
Now I have to decide whether to buy another Mopar pcm or wait for factory tuned pcm.

[FLATOUT]

I found out today that my problem was a bad Mopar pcm. I installed the factory pcm back in the car and the CEL went off and the alternator is now charging. I want to give Morgan Viper Tech. at Tomball Dodge a big thanks for helping me over the phone.
Now I have to decide whether to buy another Mopar pcm or wait for factory tuned pcm.

Wow that Mopar ECU was purchased brand new and probably only has about 500-1000 miles on it at this point. Sorry Paul.

[AbsolutHank]

Sorry about that bad luck Paul. I'll have to file that one away in the old memory bank!

[AaronFL]

Glad you found the problem. I chased the problem around for 6 months before trying the PCM. I am curious what the main cause of these to fail like this are. Does anyone know if these can be reliably repaired? I've noticed some websites offer PCM repair.

[mjorgensen]

The PCM is very voltage sensitive so any weird charging attempt or jump starting can potentially affect it. There is also no way to "repair" the Mopar PCM and Mopar does not warranty any of their products. Sorry you are having the trouble.

[FLATOUT]

The PCM is very voltage sensitive so any weird charging attempt or jump starting can potentially affect it. There is also no way to "repair" the Mopar PCM and Mopar does not warranty any of their products. Sorry you are having the trouble.

Interesting, Paul I also never changed the battery or jump started the car with the stock ECU or the Mopar ECU.

[mjorgensen]

Interesting, Paul I also never changed the battery or jump started the car with the stock ECU or the Mopar ECU.

Did not mean to imply you did, just giving information from my experiences.

[AZTVR]

I would add that if the PCM is that vulnerable to outside voltage spikes/fluctuations, then an intermittent issue in the harness, battery, ground, alternator, etc, could possibly be the cause of the PCM failure also. Just conjecturing how a voltage spike might occur without a human intervention such as jump starting or disconnecting/reconnecting something while powered up.

[ACRucrazy]

Just saw this thread now, could the UDP have anything to do with it? The PCM voltage regulator circuit that is.

I know, wouldn't seem likely just thinking out loud.

[FLATOUT]

Just saw this thread now, could the UDP have anything to do with it? The PCM voltage regulator circuit that is.

I know, wouldn't seem likely just thinking out loud.

Don't think so compcoupes and the X's run the same pulley and similar PCM's. At least the X's do.