I have a 2004 Dodge Ram 5.7 Hemi, 4x4 Quad Cab long bed I picked up at auction and have been slowly fixing it. It's drivable now, thanks to a new front axle (yes, correct gear ratio), and a rebuilt transfer case (by a local guy who's quite reputable), transmission shifts solidly, drives just fine although it needs an alignment of course.

Issue #1 if someone could help, please?

No speedometer, no indicator lights of transmission position under the speedometer. Odometer is stuck on last reading before whatever happened knocked it out. ABS light on, Brake light on.

I *think* these are all related, codes pulled up as P0501 and O2 Sensor #2 (no muffler on system, have to fix that, think it may just not read any pressure at all because the muffler is missing).

I am trying to troubleshoot WHICH sensor or if it's the ABS module itself that's out, rather than buying a ton of parts and starting to shotgun new parts at it in hopes it fixes the problem.

Is there ANY way to narrow down which sensor may be bad or how to test whether the ABS module is even getting power? I ask because a bunch of other items don't have power (radio, part of the A/C controller - stuck on hot defrost, only thing that works is the fan speed, no a/c fan clutch light, defrost light, nada), and the key dings when the driver's door is open even if the key has been taken out of the ignition.

Just trying to give an idea that there MAY be an electrical problem, so I'm trying to trace down the best way to check if the ABS computer is even getting power before I try to troubleshoot the sensors and yes, I checked the ABS fuse in the box, it's fine.

Thanks!

 

I'm thinking the front wiring harness may be the issue...

 

No speedometer, stuck odometer, and brake/abs lights on would point me to the speed sensor (or connection to) on the rear differential. Although with all of these other items, I would think loose wiring or something like that.

The service manual will have procedures to test the abs controller if you wanted to do that.

No other codes?

 

Which front wiring harness and where? Seems odd that half the dash has power (warning lights, gauges for oil pressure, coolant, etc), and just the speedo and gear position sensor are dead in the dash.

Someone had wired the stereo for an aftermarket stereo, I wired the stock one back in, but no power on the power lead. Waiting for that and A/C for another day but if they're related, do they and just those two items in the cluster get their power from somewhere else?

There were a few other codes but related to the transmission problems when it was being driven around the lot with the transfer case bad and axle bent. Had those codes reset and they haven't popped up since (low clutch pressure, incorrect 1st gear ratio, etc).

That and the O2 sensor are the only codes. That's why I wanted to power test the ABS computer to see if it's even getting power. Don't want to spend $30 on a rear sensor if it's the computer... If it's getting power then you guys thing the rear sensor replace first?

Thanks!

 

bump

Trying to figure out which harness you mean and what the easiest way to test the ABS computer for power is...

 

Sent you a pm.

 

Got it, thanks, I'm in Nashville, wish I was closer, that would be great!

 

Well, thread resurrection, slowly doing more work, all 3 tail lights were cracked/destroyed and only the left turn and brake light worked, put all those in today, had to repair the hack re-wire of the crap aftermarket dodge plastichrome ram tail lights, seems all is in the right place (used wiring diagram found online), except for these two problems:

1. I still have no reverse lights. I'm wondering if that's somehow related to the dash not displaying the proper gear the transmission is in? Anyone know how the tail lights get their reverse signal?

2. I also have no running lamps. Brake lights work, hazards work, turn signals work, just no running lamps in the tail lights or the center top brake light and there is a LAMP OUT displaced on the dash cluster, but all the bulbs, including headlights, are verified as fine. The fog lamps were removed, wondering if that is the LAMPS OUT problem?

I also put in a new ABS sensor on the rear diff, didn't fix the problem, still have an ABS and BRAKE light on the cluster, no speedometer, odometer is stuck at its current reading, no indications of gear selector (which is displayed just under the speedometer). I'm guessing it probably is the cluster??? so I got another one out of a local used truck (along with some other parts), going to swap it out tomorrow.

I re-ran the stereo wires to a stock head unit, and I still don't have MAIN radio power (didn't pull the lead to see if it's actually hot or not). If I push the clock button, the time shows up briefly, then goes away. If I put a CD in, it flashes CD, ejects the CD, but you can't power it on for actually listening to the radio or CD, the power button does nothing. I'm guessing power from the 12V ignition ON circuit to power up the radio? Is that a relay somewhere as well? Everything else ignition-on seems to function fine.

Also, all the fuses check out just fine on the above. Anyone care to take a stab at any of that?

 

Well, since it seems we still can't get answers on any of this, I'm fixing things as I go and whittling them off the list one by one.

First, we replaced the dash cluster. Still no speedometer, odo won't move, no cruise control, BUT,,, at least we have the gear selection showing up for the first time.

I tested all brake lights at the fuse box. The relays all check out, no problems there. Tail lights and running lights all have good power at the fuse and the fuses are good. Still no running lamps, I suspect it may be a ground wire somewhere, although I thought all those tail lamps shared the same ground return wire? Will go hunting for that tomorrow.

As for reverse lights, I did find that the reverse light fuse is NOT getting power. So the question is, where does the reverse lights power get its feed from? I'm guessing the transmission has a sensor on it, I may go hunting wires on the tranny and make sure nothing is crimped, broken, of frayed but does anyone know for certain the power for the reverse circuit? I'm guessing main distribution box to transmission to fuse then to reverse tail lights?

Thanks,

 

The circuit board inside the fuse box will corrode if exposed to water or moisture and things will stop working. (common problem that year) Was the truck crashed and left open were it was exposed to rain or moisture? You mentioned it needed a front axel..