2004 Dodge 2500 5.9 - P2502

[Ferrell]

Hello,

New to the boards, but was looking for advice on the following scenario:

• Driving for less than 5 mins, electrical gauge dropped to zero and flagged "Check Gages" light
• Check the codes and found P2502 which references charging irregularities
• Tested with a multimeter to find battery voltage to be ~12.4v
• Pulled alternator and it tested as good. I asked would the test show if the alternator was just starting to go out and they indicated yes.
• 3 months ago had new batteries installed and everything seems to be connected, tight, and in order
• Wiring seemed to be in good condition
• Truck mileage: 260k, alternator never replaced

Looking for feedback on what other items may be causing this issue.

Thanks in advance.

 

[Darkbloodmon]

Welcome to TDR

I had similar issues before I tore down my truck for a clutch, here is a link to that thread with my symptoms and tests. I haven't followed up yet but I ended up swapping my battery cables using a set I got from Genos and swapping the alternator for a new TYC unit from RA.

I'd try testing your cables, and making sure your connections are clean, simple stuff first. There is an ECU ground I would recommend cleaning I'll try to get a picture of it later.

 

[Darkbloodmon]

Here is a pic of that ground

This is on the driver side of the engine, and there is a bracket there that this is attached to, I removed my bracket. I forget what was mounted there, this is a manual truck for reference. There is a ground strap on the driver side of at the beginning of the trans tunnel. It comes from the back of the head and is pretty accessible from underneath, majority of the other grounds in the engine bay are pretty visible.

 

[Ferrell]

Here is a pic of that ground

This is on the driver side of the engine, and there is a bracket there that this is attached to, I removed my bracket. I forget what was mounted there, this is a manual truck for reference. There is a ground strap on the driver side of at the beginning of the trans tunnel. It comes from the back of the head and is pretty accessible from underneath, majority of the other grounds in the engine bay are pretty visible.







View attachment 128157

Thanks Darkbloodmon, will take a look and double-check all grounds!

 

[GeneBellegarde]

Isn't 12.4 V low for a normally charged battery?

 

[GrantP]

12.4 is about right with the engine off. Check them individually though. If one is ~12.6 and the other is pulling it down...you get the idea.

 

[Darkbloodmon]

Isn't 12.4 V low for a normally charged battery?

12.4 to 12.6 is nominal

 

[Ferrell]

12.4 to 12.6 is nominal

Correct, however, the 12.4 was when the engine was still running and from what I've read the batteries should be pushing 13-14v as proof the alternator is working correctly.

Additionally, quick follow-up, I double-checked the batteries, cables, and grounds. Nothing looked abnormal, but ran a wire brush over one, thankfully the gauge hasn't dropped again.

 

[Darkbloodmon]

Correct, however, the 12.4 was when the engine was still running and from what I've read the batteries should be pushing 13-14v as proof the alternator is working correctly.

Additionally, quick follow-up, I double-checked the batteries, cables, and grounds. Nothing looked abnormal, but ran a wire brush over one, thankfully the gauge hasn't dropped again.

Ah my mistake, when you said charged I thought you meant engine off after a drive; everything working as it should. You're correct though engine on 14.4v aprox. everything working.

In my experience I look at 13s as something on the system failing, unless the mfg. specifies that its nominal. I remember recently I was doing an alternator job on an 06 or 07 AWD Acura MDX and the customer got a reman from the auto parts store that when installed was only pushing 13.5v which wasn't enough to support the electronic AWD system. A day later battery light comes on. New Remy alternator from RA was pushing out 14.3-14.6v. No issues, no callbacks.

Have you replaced any parts on your system or have you just cleaned the contacts and grounds?

 

[Ozymandias]

https://mopar1973man.com/cummins/ar...error-codes/p2502-charging-system-error-r286/

Check this out.

 

[Ferrell]

Ah my mistake, when you said charged I thought you meant engine off after a drive; everything working as it should. You're correct though engine on 14.4v aprox. everything working.

In my experience I look at 13s as something on the system failing, unless the mfg. specifies that its nominal. I remember recently I was doing an alternator job on an 06 or 07 AWD Acura MDX and the customer got a reman from the auto parts store that when installed was only pushing 13.5v which wasn't enough to support the electronic AWD system. A day later battery light comes on. New Remy alternator from RA was pushing out 14.3-14.6v. No issues, no callbacks.

Have you replaced any parts on your system or have you just cleaned the contacts and grounds?

Just cleaned the grounds since the alternator was deemed in good working condition.