Major electrical gremlins; I need help

[PStone]

TDR gurus, I need your help. 2001 stock ram 198K miles. Now garaged for the last 5 months. I started having electrical issues

First: : changed headlight switch due to not lighting up. Left turn signal started fast blinking. Changed all bulbs left side
Second : truck would stall when turning on the parking lights. Reduced to driving it daytime only
Third: Truck would stall when using a turn signal.
Fourth: After researching here, I cleaned all of the grounds in the engine compartment. Left firewall, two on left fender well by the battery. Removed the air box and cleaned the grounds on the ECM to firewall wire, checked the wire with a DMM. 0.01 Ohms. So a good ground to the ECM.
Fifth: Checked all fuses and relays in the power distribution center. Cleaned with contact cleaner and compressed air. All fuses meter good, all relay coils good.

NOW IT GETS WORSE: Put everything back, cleaned all battery terminals 12.8 volts nominal not running, about 14.1 when running.
Start truck, runs about 3 minutes then dies. Wont restart. Have to pull it back into garage with the tractor.

Sixth: Buy a Centech OBD scanner from Harbor Freight. 59 bucks, great tool. Two codes, P 1689 no signal to injection pump control module and P0234 overboost.
Those are the only two codes. Get ****** off, go into the house and come back to fight another day.
Seventh: TRUCK STARTS!! but as soon as I try to turn on lights it shuts off.

I have two questions: Is the ECM on the passenger side firewall the only computer I have to worry about? And, do any of you guys have any suggestions about what I
should do next? I would greatly appreciate any feedback. I really love this truck especially after looking at new truck prices. You cant get an 8 foot bed and Im not
spending 50 grand on a weekend truck that only has to go to Lowes and the landfill.. Thanks for listening. Kinda new here so Im not sure how to put my truck profile on
the bottom here.

Pete

 

[phantomusa]

Pete you have a major short some place most likely in your lighting system
I would start by unplugging every light then put each one back in system till it kills the motor...I would pull fuses too and put them back one at a time
Electrical can get wormy and very hard to find

 

[PStone]

Phantom USA, Thank you for getting back to me so quickly. I will go there next. I am suspecting my new headlight switch because the stalling issue hadnt started until I replaced it. Thanks again
Pete

 

[BigPapa]

The PCM is on the firewall, the ECM is on the side of the engine below the fuel filter.

 

[PStone]

Thanks BigPapa. I will try to get to it this week.

 

[p-Bar]

What unique here you would think the fuses would blow if it was sucking that much power down . Put an amp gauge inline and see what the draw is.

 

[Road Dog]

It sounds like a short is drawing down the voltage but if it's not blowing fusing then you have battery or alternator issues too. With 2 800 cranking amp batteries you can build a welder.

I would connect a voltmeter and see what the voltage is doing when it stalls. Ideally it would be the ECM voltage. You can get fuse tabs that let you connect a wire to a fuse and measure there.

I'd also get the batteries load tested and maybe the alternator too.

If the ECM is losing power then it won't ever log a code.

 

[p-Bar]

And its probably why its throwing codes. Pull both battery + cables and touch one to the battery post , Does it spark ?

 

[klcammie]

Pete I feel your pain. Spent last three months fighting a short in the wiring to the oil sensor. It would cause an over boost code, after fixing that my left turn signal would blow the fuse. Found where PO had wired into the main wire with cheap connection. Don't give up.

 

[PStone]

To P-Bar: nope, not blowing any fuses. I have pulled both batteries to clean the terminals. NO spark whatsoever when reconnecting to the batteries. So no voltage draw.Where do you suggesst I connect an ammeter?
To Road dog: Thats a good idea to have the batteries and alternator tested, I will do that. You say to connect a voltmeter and see what it does when the truck stalls. Where should I connect it to , right on the battery?
To PhantomUSA: I like your idea of removing lights and fuses to try and isolate the problem.
To ALL OF YOU, THANK YOU SO MUCH FOR YOUR HELP. I will have time to get on this this weekend. Sister in Law is in town so wife wont need me for anything.

 

[Road Dog]

I would connect to the ECM power using a fuse tap:
#ad


I think you need a spare fuse for the tap.

There could be an issue within the ECM itself since that's where the voltage regulator lives.

 

[PStone]

Hi guys, HERE'S AN UPDATE!! Batteries were failing, truck wouldnt start. They were 6 years old so I replaced them. Metered the draw when hooking up the new batteries.. 2.2 milliamps. Thats nothing. Now, truck runs but ANY type of light stalls it. Cant even put my foot on the brake to put it in reverse. Should I just replace the ECM? I havent even been able to find it yet. Road dog, what am I looking for if I put a fuse tap on m ECM? Can any of you tell me where the main wiring harness goes for the parking, tail and brake lights? I want to check that for physical damage. Once again, thanks for your help.
Pete

 

[klcammie]

The main harness runs along the driver side frame rail. If you have a plug in the bed for a gooseneck or fifth wheel check the connection, on mine PO used cheap connection with no cover or tape.

 

[Road Dog]

You're measuring the voltage at the ECM when it dies. If even the brake lights cause a stall then you don't even need the engine running to check the voltage. If the voltage is fine then you may have an ECM issue.

 

[PBJ2500CTD]

Phantom USA, Thank you for getting back to me so quickly. I will go there next. I am suspecting my new headlight switch because the stalling issue hadnt started until I replaced it. Thanks again
Pete

Pete, Did you try putting the old headlight switch back in to verify your suspicion?

 

[PStone]

Good morning All,

I have removed the fuses for the reverse lights, running and stop lights. Truck will run and I can move it. I have replaced the headlight switch. The headlights come on and the truck runs so its not that circuit. I have started tracing the wiring harness from the back. I have taken apart the factory trailer light connector and verified no shorts or grounds. Today I am going to verify the rest of the harness. I will keep you posted. Thanks again for all of your help and suggestions.
Pete

 

[PStone]

UPDATE: All bulbs are out of sockets. Factory trailer light connector is out and apart. I have inspected the wiring harness from the PDC to the rear of the truck. There doesnt appear to be any chafing or shorted wires. Wiring from the PDC to the PCM is clean. All connectors are clean and dry. Step on the brakes, put it in reverse or use the parking/turn signals kills the truck. Starts right up again. I am really frustrated and unsure where to go at this point. I have the PCM out and am going to send it to someone to analyze and repair. Does anyone have any recommendations on which company to use? I really need to get this truck back in service. Once again, thanks to all for your previous help.

Pete

 

[petersonj]

UPDATE: All bulbs are out of sockets. Factory trailer light connector is out and apart.

For clarity, are you saying that when all bulbs are out of sockets the engine still dies when you step on the brake, put it in reverse, or turn on the park/turn lights? Or, are the bulbs back in their sockets when you do the test?

If the bulbs are out when you do the test, then you can disregard the following.

But if this is not the case, I think you have a ground problem - not a PCM or ECM problem, nor a short. For example, if the ground circuit from the lights you turn on are shared with the PCM ground circuit through the body, then it is possible to shut down the PCM when a light circuit is turned on if there is a significant voltage drop in that ground circuit.

Most of the time visually inspecting wiring connections and /or physical cleaning the connections will take care of poor electrical connections, but.... not all of the time. Many times I have seen what appeared to be solid and clean connections still have a poor electrical connection in terms of continuity.

The most reliable troubleshooting technique is to perform is a voltage drop test in the ground circuit portion of the problematic lighting circuits (which must be turned on during the test) that kill the engine. Typically a ground path from a tail light or a brake light bulb begins at the bulb base and then goes to the truck body, then to the truck frame, and finally to the ground post on the battery. The total voltage drop from the bulb base to the ground post on the battery should be less that .2 volts (two tenths of a volt). You should have some voltage drop reading because even good wiring circuits have a very small voltage drop any time current is flowing. If your meter reads zero, then your meter has a poor connection.

The same test can be performed in the positive side of the same circuits.

If this were my truck I would take the time to perform these voltage drop tests to prove that the electrical circuits are in good operating condition.

- John

 

[PBJ2500CTD]

I second what John stated. I believe you have a wiring issue. A multi-strand wire can break all strands and have but one strand remaining which will still read continuity with an ohmmeter. The one remaining strand may not be able to conduct the current necessary to activate the circuit, in which case the current will take the path of least resistance through other circuits. I have some questions: Are you applying the brakes when you select reverse, or are you selecting reverse without applying the brakes? Have you tried activating the 4-way flashers? Does the truck die when the lights flash? Are all four corners illuminating with equal brilliance? You stated that the left turn signal flashed more rapidly. This may be an indication which circuit is causing the issue.

 

[Missouri Mule]

Do you have a tilt steering wheel/column. Members in the past have problems like yours. When the steering wheel is tilted up it pulls the wires going to the ignition switch out at the connectors. Don't remember all symptoms or if your connector is on the steering column (under dash).