Hello all,

I have a very tough problem that I have been trying to troubleshoot for about a month now. I have searched until Google just started to say: Take it to a dealer because we have no idea.....

Truck: 2003 Ram 1500 5.7L, Auto, 4x4, no chip in key, no starter disable, no alarm.

Problem started randomly one day with no symptoms beforehand. I go out one day to leave and truck won't start. Turn the key and I get all the dash lights, but gauges are all dead and the trip computer just shows dashes. Does not attempt to even turn over. I worked through the normal of checking the starter, battery (10months old), jump pack to make sure battery wasn't bad, fuses, etc. Everything else works, blower, headlights, wipers, stereo, etc. After some reading I started with replacing the ignition switch which did not resolve it. After this I was preparing to have my son help me with testing voltage at starter one day and I had left the key to ON position for 10-15 mins or so. I told him to give it a shot so he knew what I wanted him to do.. and bam it fired right up. Next few times it did as well, so I figured that the computer maybe needed to learn the new switch or something dumb. Next day, go to start.. dead again. I was able to repeat process with leaving key in ON position for x amount of time (always changed) and after a bit the gauges would all fire up and truck would start. Turn off several times and would always re-start. If I left it sit off for 15 ins or so, it would then go back to no start. (repeat key ON procedure to get it to run again)

When I got it to run, I took it to my buddy's shop to scan it since my personal scanner doesn't do what his Snap On one does. We went over testing stuff and the only code was a P1793-TRD Link Communication Error.

Figured it could be tranny control module going out again, however the last 2 times that thing went out, I was still able to start truck and not have these problems. I even tried a spare TCM that day and no change. Also worth noting that the key trick to pull codes doesn't work any longer either.
After running though all kinds of testing it just all together will not try to start with the aforementioned key in ON position and wait. So I figured that it has to be computer. Ordered a new one last week, plugged it up... nothing. Other day I went out and pulled every single fuse to check them, as well as swapped ECM related relays around. Zilch !

Anyone have any ideas on this ? Every single time I think I can pin point issue, it doesn't add up because I was able to let it sit in ON position for x amount of time and then it would fire up and work as normal. Almost rules out wiring issue, shorts, etc.

Thanks in advance for anyone with some insight..... I am going to go out there in a few and try to look at wires/harness/etc.

*Edit*
Another thing to toss in there... with old computer and with the new, my Hypertech Programmer gives error: Unable to retrieve VIN. (I expect this on the new one as I am unable to remove the programming from the old computer). My regular scan tool gives no errors and shows no codes with either computer.

 

I may have found the problem, or at least after reading this thread and tearing my power distribution center apart....

https://dodgeforum.com/forum/3rd-gen...mystery-2.html

Corroded PCB and some traces that came apart.

Dealer wants $500+ for one. I am gonna look around and will update when I figure out if I can repair or replace and if it solves problem.

 

Check for C-Codes... Hold the trip reset button on the dash while turning the key to the on position...

Post up the numbers that appear EXACTLY as they appear on the dash...

It truly sounds like you have a serious electrical problem... or a PCM and/or TIPM that crapped out....

 

This is how the power distribution center looked when I pulled it apart. This was the worst part and the traces were off the board. The way they came off, I am unsure exactly what pins were tied to that dime sized area and don't even want to guess causing further damage. Since there were some other areas that were starting to look the same, best thing is for me to get a used one off EvilBay. I am not going to pay $500 to the dealer when I can pay half that and get one from the south where there is not such a risk of corrosion.

I will update when I get the part. I have noticed several threads that are similar and they never get answered on if they are fixed.

 

if this is the TIPM you'll likely need to get it programmed... if it's just the PDC then you can just grab a used one from any truck within your model year up to 2004 and down to 2002.

 

Well I got the power distribution center today and installed it. It did not include the FCM, I re-used my original one. Everything connected and dielectric grease where needed.... back together.... still no gauges or start.

Progress being made though as I now have a temperature showing on the trip computer, where it used to be just dashes before. Problem is... temp is 130 degrees...... (actually 39 right now) Everything else is just dashes except trip odometer retains it's last mileage.

New development is that the radio now no longer works, yet windows, doors, seat, wipers, all lights work. I pulled the C Codes and I got:
AA 00
00 00

With the trip computer working and now being temp pegged that something either needs reset, or the FCM could still be bad yet. I even tried putting old computer back in (as I am trying to save my Hypertech programming).

I called dealer and parts tells me $500 (everything is this price.. the PCM, PDC, FCM).. but they couldn't tell me if it needs programmed. I figured since it is the same module that it wouldn't need programmed. They put on with service adviser who seems to me just wanted me to bring the truck in because "anything dealing with computers now a days needs to be programmed". I asked him if I could just bring the module and naturally they said no, need whole truck. (A1 Cardon was able to program just the computer before it was sent to me)

Anyhow.... so if it is a FCM, does that need VIN programmed in as well ? Or is there a way to reset it or even test it ?

I have been over all connectors and such several times.. also triple checked every single fuse on the new PDC to make sure everything was good there. I did not try swapping around relays yet... but I am thinking that may not be the underlying issue.

 

hmmm... according to this YouTube video, it may not need to be programmed. This guy just swapped with one from yard, and I noticed the one he pulled out was different part # than the one he put in.


I hate to keep throwing money at this problem..... it is getting annoying real fast.

 

Just some more info I found while searching on if the FCM needs to be programmed or not. Nothing is mentioned about programming it, and that is apparently directly from Dodge.

As messages are sent over the CAN bus circuit, the Front Control Module (FCM) reads these messages and controls power to some of the vehicles electrical systems by completing the circuit to ground (low side driver) or completing the circuit to 12 volt power (high side driver). The following functions are controlled by the FCM:

• Front turn signals
• Stop, turn signal and tail lamps
• Front and rear hazard warning lamps
• Headlamps
• Fog Lamps
• Daytime running lamps - if equipped
• Horn
• Windshield and liftgate wiper and washer systems
• Transfer case shifting
• Trailer tow wiring output
• Rear window defroster power and timing
• Air conditioning condenser cooling fan

The FCM provides the following features for the above function:

• It provides a illuminated approach feature that turns the headlamps on when the vehicle is unlocked with the Remote Keyless Entry (RKE) transmitter.
• It flashes lamps in response to turn signal, RKE and Vehicle Theft Security System (VTSS) inputs.
• It sounds the horn in response to RKE and VTSS inputs.
• It turns off the horn in the event of excessively long operation that could otherwise damage the horn.
• It turns off the windshield washer motor after 10 seconds of continuous operation to protect the motor.
• It minimizes voltage variations to the headlamps to extend bulb life and to equalize the light output from the lamps, which might otherwise differ due to variations in wiring resistance.
• If the headlamps are left on, it automatically turns them off after eight minutes to protect the battery from discharge.It monitors battery voltage and turns off non-essential functions such as the fog lamps, rear window defogger, and heated seats if necessary to conserve battery power.
• It operates the high-beam headlamps at reduced intensity by pulse-width modulation of the power supply to provide the daytime running lamps.
• It provides the variable delay intermittent windshield and liftgate wiper time delay features, and the vehicle speed sensitive windshield wiper delay variation.
• It acts as a link between the CAN bus network for critical powertrain and anti-lock brake systems and the network for body and interior modules.

 

Well.. I am officially out of ideas, and ready to stick a match in the damn tank.

FCM arrived today, put in, no change. Pulled battery to allow discharge, no change, Swapped back in the new main computer, no change.

So I have been through Computer, ignition switch, TCM, PDC, FCM. The only change was when I put in the PDC, I got the trip computer back but it shows constant 130 degree's.

Still same problems and out of ideas. Anyone have any for me ? My only idea right now is a cold beer.

 

The TIPM might have failed.... you might need a new one of those, and I'm pretty sure those have to be programmed at the dealer w/ the truck in the shop...

If it's not that then you're going to have to start tracing out wires for shorts, which is really freakin difficult and even more time consuming.

My bet is on the TIPM though...

Also the C-Code you got that was AA 00 indicates "PCM messages not received." which points directly to the PCM and likely is being caused by the TIPM...