Here's my problem - I'm having the same issue many others have reported with their ABS/Brake warning lights coming on intermittently. I have replaced all four of the abs/speed sensors (both wheels, diff & trans), but the problem persists. What's more, the engine has begun to stall on me (no Bus message) while the ABS/Brake lights are on - so far it has died three times, and almost a fourth (putting it into neutral at highway speed revived the engine).

All three times I have gotten it going again by resetting the PCM (pull neg batt cable, unplug PMC connector nearest firewall & wait ~5 minutes) but I really need to get this resolved fast. My wife is *very* pregnant and could be delivering just about anytime, and we're depending on the "D" to get us to the hospital when that happens!

I *think* I need to replace either the PCM or the ABS controller, or possibly both. What I need to know is how to determine which one is causing the problem. I would think that I could test it by disconnecting the ABS controller, and then driving it around in a large parking lot or something to see if it still stalls; if so, then it must be the PCM, as the ABS would be out of the loop, correct?

I'll take it to the dealer if I have to, but I'd really prefer to fix this without bending over for them!

A little background on the stalling issue might be relevant:

A week ago I was going ~45mph when I had to make a sudden stop. The ABS/Brake warning lights were lit at the time, and when I nailed the brakes, the wheels locked up (all 4 I think!) which was no surprise considering the state of my ABS system at the time. I managed to bring the beast to a screaming halt safely, and shortly thereafter (~10 minutes) the engine stalled. When it happened I was a block from home going about 20 mph, when I realized that the engine had stalled! The truck refused to restart, so I had a friend tow it back to my house, where I read up (on this most excellent forum - THANKS!!!) on how a PCM reset might fix the problem - and it did. Thank God! The truck never stalled prior to this incident, but has since stalled twice more - and each time a PCM reset got me going again. I wonder if I somehow overloaded the ABS controller when I locked up the brakes?

Any thoughts/ideas/suggestions?

Thanks!!
LtFG

you could check the brake fluid, as that will set off brake lights in the dash.

it could be the ABS computer, or the PCM on its way out, next time it stalls out take a sealed bag of ice and put it on the PCM, if it starts up that way replace the PCM.

unfortunately the only way i know of to diagnose the ABS is with the DRBIII tool which is usually a dealer only tool due to the price tag

Thanks Sharpshtr.

I guess what I'm looking for is some way of logically proving that either my ABS controller or PCM are going bad. I'll take it to the dealer if I have to, but I just don't have much free time (or $$) with a baby on the way, so shouldn't there should be some way to figure this out without their expensive DRBIII?

Correct me if I'm wrong, but if the PCM is dying, it should be storing codes which I could read with my trusty CAN/OBDII scanner. No codes means the PCM is probably not responsible, right?

Questions:

1. I've read that the truck will still run/drive without the ABS module connected, so if I disconnect it, the truck shouldn't stall if the ABS module is causing the problem, right?

2. If I disconnect/remove the ABS module, and the engine still stalls, then it's definitely the PCM, correct?

Thanks!!

thats the problem with some of these computer controlled systems, they are VERY hard for the shadetree/backyard mechanic to diagnose.

yes the truck should still run and drive without the abs module, you just wont have any abs, and the lights will stay on if the truck stops stalling i would replace the abs module as that is the most likely cause at that point. however if the truck doesnt stall that doesnt necessarily point to the PCM, there are so many different electronic modules on these trucks that can cause problems. Also the PCM will not always throw a code when it goes bad, unfortunately (although if it does your OBDII should be able to read it just fine.)

Not necessarily, when I had my abs module out for its rebuild mine stalled if I didn't tap the throttle after I started to engine brake, I was towing so when it did stall it wasn't to fun without power steering. Just my

Update time.

Although I haven't had any more stalls, my ABS/Brake lights still turn on every time I drive the truck, *except* for first thing in the morning, when the truck (& air) is cool.

Sharpshtr mentioned using a bag of ice to help diagnose my problem, and that got me thinking. Since the truck is fine when it's cold, I decided to 'test' the ABS controller & PCM by putting ice on them when the truck is warm. I started with the ABS module, by placing a large plastic bag with ice on top of it, and letting it sit for a half hour or so. Then, I took it for a drive to run some errands, and the lights came back on almost immediately. When I got to my first stop, I moved the ice bag over to the PCM, to see if that made any difference - and it did! No ABS/Brake lights (and more importantly, no stalling) all the way back home. I'll do some more testing, just to verify my results, but I guess this means I probably need to replace my PCM, or have it rebuilt.

cant rebuild the PCM needs to be replaced, and yes unfortunately it sounds like your PCM may be on its way out, but more testing doesnt hurt unless the PCM gives up completely

you can buy pre-flashed plug and play units from ebay for like $250