No serial number that I can see, just a part number. One nice thing about working on a somewhat older car is that the electronics aren't crazy complicated. By the late 90s, however, all bets are off.

My buddy did a head job on his daughter's Plymouth Breeze with the 2.4L I-4. During reassembly he swapped the connectors for the coil pack and the camshaft position sensor. Yes, they're identical. Stupid. Anyway, the PCM was instantly fried. He went to a yard and bought the PCM out of another Breeze of the same year. Same engine, same transmission. No start. In that case the PCM *was* programmed with the VIN of the original vehicle and it simply wouldn't work in another. What a pisser. Looks to me like someone is trying to get cars off the road when they need repairs.

Anyway, I hear what you're saying but I don;t think I'll run into that on my ABS issue. Thankfully.

 

Are you saying you need a ABS scanner just to clear the codes. Pull the fuse will not clear it? What is this about the bleading?

Sorry for all the question when I was tech anti lock system was isolation and dump valve. No motors

 

The manuals say that the ABS system cannot be "properly" bleed without using some type ABS scan tool.

 

Yeah, don't know exactly what it does, but you can't bleed the brakes right without it. It somehow works the motors so fluid will go though them and aligns them where they need to be.

 

Then my question is do I need a different ABS tool for each of my three cars? I have a '94 Camaro Z28, a '94 Chevy S10, and a '07 Chevy Silverado. Will they all take the same scan tool? If not, this could get really expensive to flush and refill the brake fluid on my two '94s.

 

not trying to jack your thread just a quick question could an almost dead battery cause the abs to turn off to save power

 

Basicconcepts, I don't have any documentation to prove it but it is very likely.

The ABS VI system uses a lot of juice so an activation when battery voltage is very low could pull battery voltage so low that the engine stalls. You wouldn't want that and neither would GM.

The ABS controller does have two low current, battery voltage inputs: one at pin B10 from the 5A ABS BATT fuse and one at pin B11 at the 5A ABS IGN fuse. These feeds would allow the ABS controller to monitor battery voltage and determine whether it is sufficient for ABS operation.

The ABS controller gets a large current feed via pin C1, a huge wire that comes directly from the ABS relay which is fed from a large fusible link right behind the battery.

 

Another update. Hit the U-Pull-It yesterday and headed right for my favorite 94, now largely a stripped hulk. Fortunately, the ABS controller was there. Awesome, because there was only one other 4th gen there, a 95 (Polo green with a tan interior), and 95s use a different controller.

Getting the controller out was super easy becasue someone had already removed the steering column and brake/clutch pedals.

I was also there for an EGR valve or two, having done some research and learning that most 3.1, 3.4, and 3.8 V6 engines used the same EGR valve from 1988 through 1995. That was guaranteed to be there. I got 2, taking the ones that looked the freshest. Total cost for that trip was $42 so I was thrilled.

When I got home I plugged in the controller and decided to test it by hooking up the spare motor pack by itself. I expected all 3 of the motors to pulse, showing that all 3 drivers in the ABS controller were good. I was surprised and concerned when turning the key to run did absolutely nothing. None of the motors so much as twitched. I thought Oh crap, this controller is totally fubar.

When I went to turn off the key, though, I realized that the ABS INOP warning lamp was off! So there was hope after all. I unplugged the spare motor pack and hooked up the harness connector to the installed hydraulic assembly. I turned the key to run again and, after a second or two, the ABS INOP warning lamp turned off. Could the system really be fixed?

I permanently installed the controller, reassembled the dash, and took the car for a test drive. Brake operation was normal and I never got a warning lamp. I took my wife to the airport later and had a chance to run at 75 mph for a while. Still no warning lamps.

I guess the acid test will be when I have a panic stop. It's raining here this morning for the first time since I got the car on the road so I'll go out and do a few hard stops to see what happens.

 

Went for a test drive on the wet roads and it seems like the system is really fixed. No ABS INOP light for one thing. I made a few moderately hard stops getting ABS to kick in and the only thing that happened was that the LOW TRAC light came on just like it should. Amazing. I wonder how long the system has been broken.

I wondered about something else so I tried it. On a long steep climb I floored the accelerator and one of the rear wheels broke loose. I kept the spin going for awhile to see it the LOW TRAC would come on. Nope. In retrospect I guess that makes sense since the ABS controller needs to see a brake switch input to activate ABS.

Here's the inside of the bad ABS controller. It's easy to see where the problem is.

Yeah, right...

FWIW the output part of the controller, the part that operates the three motors in the hydraulic assembly, is on the RH half of the circuit board. The big aluminum bar across the board is a heatsink and HD transistors are clamped to the heatsink by the black metal bands. At least one of those transistors is bad, probably more.