It seems like the ABS system is a big mystery. Neither Haynes nor Chilton have any information about it. So here's my problem:
2001 LT 4-door 4WD. Replaced both front hubs less than a year ago. (They were noisy and ABS light came on intermittently). Everything was fine for about 6 months. Then ABS light would come on occasionally while driving at low speed, but go off over about 10mph. Deteriorated to the point where it now stays on all the time. Had a shop check it and they said the right front sensor was bad-need to replace the hub. The ones I installed were under warranty, so I got a new one. Before actually installing it, I just hooked up the sensor wire. The initial 'start' test (light comes on, light goes out, light comes back on) still fails. I also put a meter to both front hub sensors and they read the same. (within spec as far as I can tell).
So what I need is a wiring diagram/picture of a 2001 vehicle that shows the cable(s) going from the sensors back to the ABS control unit. I found one on this forum for a 1997, but the number of wires and connectors don't match. Any help/ideas appreciated.

 

Have the truck's computer scanned. Most OBDII scanners will scan the ABS system. I have the ABS/Brake combo lights at times, and found out it was actually the EBCM acting up. So I need to have that fixed.

 

Throw the Chilton and Haynes manuals in the trash, they're worthless. Half of their information is incorrect and the other half is missing! Have someone retrieve the DTC's with a capable scan tool and we can help you troubleshoot it.

 

hmm my abs light comes on intermittenly as well. but I doubt it's for the same reason. mine comes on when I unplug it when I go play in the mud. weird....(way to touchy and prevents me from stopping too often)


check the connections at the abs module?

 

I have a scan tool (DigiMoto), but it doesn't show ABS codes. The shop that checked it said the code showed a bad right front sensor, but they didn't tell me the actual code. They did it for free, so I'm not sure about going back and having them do it again to give me the code.
I suspect it's a bad wire-just need to know which connector on the ECBM it goes to and/or the pinout.
And if it is a bad ECBM, can the electronics portion be separated (and replaced) from the hydraulic/pump section? Looks like it's just 4 screws.
Thanks.

 

This link will take you to the TSB for ABS activation below 5MPH. You can go through the test procedure on the sensors to see if they are working correctly.

http://www.alldatadiy.com/alldata/AF...5789/121073096

 

Well, I dug into my ABS problem today and hopefully came up with some info for future members. The particular ECBM on my 2001 is a Kelsey Hayes unit. There are 2 connectors on it, underneath, towards the back. One is a 2 position and provides 12v and ground, always on. The other is a 2x8 position, labeled A1-A8 and B1-B8. This is where the sensor wires come in. The Left Front wheel sensor connects to A2-B2, the Right Front uses A3-B3. You can put an ohmeter across these pairs to measure the wheel sensor resistance. A good reading is about 1100 ohms. There are some other posts that mention using a low-range voltmeter to check the output while spinning the wheel. (easier said then done with WD..). Bottom line, if the readings at this connector are correct, you most likely need to replace the ECBM.

Now the bad news, that appears to be my problem. has anyone separated the electronics part from the 'pump' part? Can it be done? Is it wise to do it?

 

I wanted to know the same thing, but after searching the net it looks like the second Gens are sold as abs module and pump. I been looking at solving this issue on my 01. Going to try the trouble shooting tips I have found so far and also going to visit my favorite Junk yard and pull a matching module and pump. I saw something about getting the modules rebuilt for like 250 or another on this forum.

 

I have a similar problem as well....my abs and brake light will just come on out of nowhere...pretty sure its the ebcm, but those are defintly a little pricy

 

Could be an internal ground failure or an external ground failure.

At least thats what I've read on other boards.