Voltage regulator in PCM fried??

[ArkansasDodge]

Hello everyone... After spending all day researching 4th gen ram charging systems I have a problem to share.

Yesterday, I finished rebuilding (cam, lifters, etc) my 2015 ram 1500 and everything was charging correctly upon completion.

However, two nuts on my rocker arm assembly were making a slight tick on the driver's side, so I removed the cover this morning and tightened everything. While reassembling the engine I got excited and attached the battery cables before the alternator . A second later I managed to create a large spark by grounding one of the cables or wiring harnesses (I didn't see clearly).
The truck starts and runs great, but now the battery charging light is flashing and the charging gauge is below half on the scale.
The PCM regulates voltage, so I'm assuming it needs replacement. Any suggestions or thoughts about a bypass or fix without a new PCM?

Thanks guys for any info. I have searched this forum extensively today and can't find anything.

 

[crazykid1994]

Checked output of the alternator?

 

[ArkansasDodge]

I checked the 13mm nut on the alternator and it was 12.4 volts with engine dead and 13.5 while running.

The battery light keeps flashing along with the CEL. I'll check the code tomorrow when I get a chance.

Just thought someone might have an idea what to check. The PCM fuse and ASD fuses were both fine so I'm out of ideas now.

 

[ArkansasDodge]

Ran a scanner today and am getting no codes associated with my charging system.

However, the three codes present were possibly associated with a PCM working incorrectly.

P0201 fuel injector #1 control circuit

P0301 Cylinder #1 misfire

P0303 Cylinder #3 misfire

The engine is so smooth and quiet I've eliminated considerations of mechanical issues and am sure its electronic.

Any comments or clarifications about my assumptions? Thanks guys for any feedback!

 

[yoda]

Do you have battery voltage at the alternator? The large terminal with 13 mm nut?
You probably blew the large fuse attached to the positive battery cable.

 

[ArkansasDodge]

I stated it in the long-winded introduction: with an analog multimeter 12.4v dead engine and 13.5v running. The low voltage dash light is flashing.

Pulled the positive terminal off my battery while it's running and engine stalls.. on old engines that usually meant bad alternator.

My terminal links are not blown. A conductivity test confirmed a connection is made on both terminal links at the battery.

 

[yoda]

Sorry i missed that, hmm that doesn't make sense, if your reading 13.5 running, your alternator is charging, is your electric power steering working?

 

[ArkansasDodge]

Power steering works great with the truck started, just isn't maintaining the voltage.

My concern is the alternator is fine and the voltage regulator in the PCM is not signaling the alternator to add voltage to the system.

 

[yoda]

Possible but not likely, Im trying to think of a way to help you out with some tests to perform, tough without the proper equipment

 

[yoda]

08 - Electrical / 8F - Engine Systems / Charging / Operation
OPERATION

1 - PCM

2 - PDC

3 - Battery

4 - Generator

5 - Feed Back Circuit B+

6 - Control Circuit

The charging system is turned on and off with the Powertrain Control Module (PCM) and ignition switch with engine running. The field circuit will not be energized until engine is running and ignition switch on. This voltage is connected through the PCM and supplied to one of the generator field terminals (Gen. Source B+) at the back of the generator. The generator is internally grounded. The generator regulates the field using pin-1 of the field connector (high side driver).

The generator is driven by the engine through a serpentine belt and pulley, or a decoupler pulley arrangement.

The PCM receives a voltage input from the generator (5) and also a battery voltage input from the Power Distribution Center (PDC), it then compares the voltages to the desired voltage programed in the Electronic Voltage Regulator (EVR) software, and, if there is a difference it sends a signal to the generator EVR circuit to increase or decrease output. It uses a Pulse Width Modulation (PWM) to send signals to the generator circuitry to control the amount of output from the generator. The amount of DC current produced by the generator is controlled by the EVR circuitry contained within the PCM (1).

All vehicles are equipped with On-Board Diagnostics (OBD). All OBD-sensed systems, including EVR circuitry, are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in electronic memory for certain failures it detects.

The Check Gauges Lamp (if equipped) monitors: charging system voltage, engine coolant temperature and engine oil pressure. If an extreme condition is indicated, the lamp will be illuminated. This is done as reminder to check the three gauges. The lamp is located on the instrument panel.

Voltage is monitored at the B+ terminal stud to insure it is connected. If the B+ cable is loose, the PCM will shut down generator field. Because of this new feature, pin-2 of the field connector is internally connected to the B+ terminal.

 

[ArkansasDodge]

Thank you Yoda! I was already convinced I grounded a hot PCM line and fried something, but now I'm feeling more confident.

The Chilton's manual for the 4th gens is horribly vague. The charging system was only provided for a 3.6L or some vehicle that didn't apply to the 5.7.

I ordered a pcm yesterday with the vin programmed into it. I'll post the results tomorrow when it arrives.

 

[madtrucker2016]

Read the whole story hope it all works out for you . Could you get a used pcm from a junk yard for less money. One that matches up to your truck

 

[ArkansasDodge]

300$ wasn't too steep to get it running, but I'm an idiot for making the problem. I live in the middle of nowhere so the internet is my best option for parts. Thanks guys. I'll post tomorrow.

 

[Jpercy14]

Well..

 

[HEMI-FI]

Well..

 

[ryanpaulaf1]

So what was the issue after all?