I have a 2002 Ram 1500 SLT 4x4 Quad Cab 4.7l. I have a boatload of issues with the truck.

-ABS light, Check Engine, Brake, Airbag, No Speedo, No Odometer (yes I replaced the rear ABS sensor on the pumkin)
-No reverse lights
-Truck starts to vibrate (not in the steering wheel) under load in high gear around 1500 RPM. It goes away once I apply a lot of throttle and it down shifts. It'll come back as soon as I try to maintain cruising speed
-No AC or rear window defroster (buttons dont illuminate and are unresponsive) However, the heat works but only high temperature and it'll only go to vents on the windshield. No controls work besides the blower speed.
-Engine turns off randomly. Sometimes it's just at idle and sometimes it's when I'm braking. I've checked for loose connections or damaged wires but everything looks pretty good. I've wiggled wires while its idling and nothing. When it happens, the rest of the electronics stay on. The engine doesnt struggle at all, it just turns off.

Things I've done:
-Replaced the PCM (the computer on the passenger side firewall-had it programmed as well) & ECM (attached to the fuse box), replaced the fusebox, replaced the climate control unit, replaced the instrument cluster=nothing changed
-All fuses and relays are good.
-Only code that comes up is for the radiator fan. I tried jumping the AC fan and it wont start so that is a known problem - I'm working on getting a replacement.
-I jumped the compressor and it turns a little (struggled)...don't really know if that works.
-Cleaned the TPS.

I've hit a brick wall. Nothing I've done has changed anything. I'm open to any and all suggestions.

One thing that has just recently come to mind and I've started investigating with no success is as follows:

The previous owner said he replaced the engine a few years back with a newer 2005 (from what I recall him saying). I'm thinking that maybe he didnt swap the computers and wiring like you're supposed to. I've been trying to confirm which engine I have in there, but I can't find any information on how to identify the year of the engine. I think I read somewhere that there is a tag with all this info, but I think that is long gone. Can anyone tell me where I can find the casting number? I'm going to get under the truck after work and look around today.

If anyone could help me figure out which engine I have, at least then I could verify if I have the correct computers and wiring. I'm praying that this is the cause of all my problems (or at least the major ones)

Hope someone can help!

 

A simple corroded terminal slightly touching another can cause a major malfunction to so many things. Could be from under the fuse box to the trailer wiring plug. Check those. also i have read where a wire is prone to rub behind the AC compressor and eventually grounding out. Yours could have been re routed but its worth a check. It has to be something grounding or shorting out that is causing this. The original pcm shouldn't cause these things to go haywire if anything it would have affect the engine. I would trace each wire loom checking for stabs or cuts. Particularly around the engine bay. Like i said before something like a simple single strand of wire from a cut wire could be crossing onto another cut wire will cause this. I've had my issues with wiring and it always ends up being something simple and easily looked over. I wish you good luck.

 

Thanks for your advice. Let's say a wire did rub through and short out. Would that wire need to be replaced or would I simply need to patch up that spot?

 

If there is enough slack, cut out the abraded section, solder, electrical tape and heat-shrink should do the trick. If there is no slack, cut and solder in a short piece of the same gauge or larger, electrical tape and heat shrink.

 

Not sure how the cooling fan could throw a code - there is no interaction with the computer for that. The "fan only blows fast" is usually the resistor block. It's easy to change. The vent issue is usually the infamous "blend door" problem.

 

got it. I plan on spending a few hours tomorrow looking over everything. Hopefully I find something.

 

Well I'm showing a P1491 code on the instrument panel. I've swapped around the relays and I've replaced the whole fuse box so it's definately not the relay.

If the cooling fan doesn't work, would that be reason for the AC system not working?

 

That's a bogus code. It does reference the e-fan relay, but you don't have such. There is a reference in about.com auto repair suggesting the PCM is bad. Not good news! Hope it's wrong.

 

http://autorepair.about.com/library/faqs/bl138h.htm

 

This is likely your issue. The wiring harneses us data-canbus wiring which relies on switching electrical pulses fromthe pcm to the cluster. If there is a different wiring harness used or engine, then you can have some sero=ious electrical issue's. 2002 harness and connectons are slightly different from a 2005 harness.
Go in the FAQ section an you can download the manuals and compare the wiring connections to verify ther differences.

I'm not excatly sure on casting numbrs and years??