ABS dead, dying?

[LTb1ow]

So, my dash is screwing with me.

As of now, on startup and few a few minutes, the low trac, and brake lights flicker. Then sometimes the ABS/ASR/airbags go off or stay on. Sometimes they all dim and flicker, other times they all go off minus the ASR.

My car is got gremlins. :(

Also, we tried to scan it, the scanner reads the PCM but can not read the ABS/safety stuff.

Ideas?

[NastyEllEssWon]

you might want to check out the abs block on the port side of the vessel. have you checked your fluid too?

[The_Bishop]

I had a persistent ABS light, too. Then I put the ABS unit and computer in the garbage and grounded the correct wire. Now, no more ABS problems and the light is off!

:D

[NastyEllEssWon]

wanna send me some more details on what you did to delete the abs and lose the light...i have no abs cause of my rear and i want my light GONE

[The_Bishop]

I used a kit from SJM, ended up with a line lock and an adjustable proportioning valve.

Pin A7 on the EBCM drives the ABS IOP light in the IP. A Light green wire. Tap in and ground this to disable the IP light. ECBM is located up in the driver side kick panel.

Kits can be found here:
http://www.sjmmanufacturing.com/cam_brk_lt1.html

[LTb1ow]

Ok, I can not delete my ABS. Parents gave me the negative on that one.

Did some research and this is what I got.

The ABS is affiliated and controlled by the EBCM (electronic brake control module) If you stick your head under the drivers side dash and look all the way up at the up most point on the drivers side you'll see a silver box. Thats that beauty.

The Air Bags are controlled by the DERM module and a couple of dual pole and arming sensors throughout the car ie. the front and one under the console. This has a capacitor in it that holds power for a certain length of time.

Now who wants to explain why the damn air bag light is on if I just screwed up the ABS part?

[NastyEllEssWon]

is it in the same location as on the ls1's? and if i just ground out the corresponding wire itll kill the light? i could use that gone

[LTb1ow]

Well I am kinda giving serious thought to bringing it to a dealer. But I just don't want to leave my car with anyone :(

Also, I am not sure what kinda scanner Adam has but it looked pretty professional, I am wondering if a dealer or other shop would be able to do anything more than see that its not communication and say oh well.

[WildBillyT]

How long ago did you install your MSD?

[sweetbmxrider]

i could see if i can get my hands on a dealer scanner before you bring it there. let me talk to my guy before you do anything drastic

msd was in the car before he deleted the traction control. that has since caused said issues.

[LTb1ow]

Yea, I also have an aftermarket alarm too. Dunno wherther that screws with that stuff.

[WildBillyT]

i could see if i can get my hands on a dealer scanner before you bring it there. let me talk to my guy before you do anything drastic

msd was in the car before he deleted the traction control. that has since caused said issues.

Thanks. I was looking for a no BS description of what was going on and couldn't find one.

[LTb1ow]

Thanks. I was looking for a no BS description of what was going on and couldn't find one.

When I get a break I will write more details up for you.

Ok, had the TCS setup. I bought a regular throttle cable and swapped it in. Forgot to plug in the TCS motor and started the car up, car threw the ABS/ASR and air bag lights. Figured it was normal and plugged the TCS motor back in, no change. Went to get the codes read and the scanner can not communicate with the ABS or safety computers. Reads the PCM fine.

Possible faults:

Fried the ABS and safety comps.
Bad ground when I installed the N20 kit.
Messed up something when I was screwing around under the dash with the throttle cables.
Low voltage from low idle and or bad alt.

[sweetbmxrider]

The ABS system is controlled by a microprocessor based Electronic Brake Control Module (EBCM). Inputs to the system include four wheel speed sensors, brakes, ignition switch and unswitched battery voltage. Outputs include three bi-directional motor controls, three lamp controls, two solenoid controls and the system enable relay. A serial data line, located in terminal 9 of the Data Link Connector (DLC), is provided for service diagnostic tools and assembly plant testing.

The EBCM monitors the speed of each wheel. If any wheel begins to approach lock-up and the brake switch is on, the EBCM controls the motors and solenoids to reduce brake pressure to the wheel approaching lock-up. Once the wheel regains traction, brake pressure is increased until wheel begins to approach lock-up. This cycle repeats until either vehicle comes to a stop, the brake is released or no wheels approach lock-up. Additionally, the EBCM monitors itself, each input and each output for proper operation. If any system fault is detected, the EBCM will store a DTC in nonvolatile memory.

On a EBTCM, the ABS portion of the module operates the same as a EBCM. A EBTCM is used if the vehicle is equipped with either the Enhanced Traction System (ETS) or Traction Control System (TCS). The ETS or TCS portion of the EBTCM monitors wheel spin slip through the drive wheels speed sensors. If the wheels begin to slip, the EBTCM determines the desired wheel torque needed to minimize wheel slip. This information is sent to the PCM through the Serial data link. On models equipped w/ETS, the PCM controls engine torque by ignition retard and transmission shifts. On models equipped w/TCS, the PCM controls engine torque by ignition retard, transmission shifts and applies brakes several times until the vehicle regains traction. Once the vehicle regains traction, brake pressure is decreased and engine torque reduction is no longer requested. This cycle repeats until traction control is no longer necessary

[LTb1ow]

Hmm, so no where in there are airbags mentioned, coincidence?

[BonzoHansen]

You should search ebay for factory service manuals. I grabbed a complete set for a 99 for $50. It will tell you most of what you want to know. Very valuable IMO.

Doesn't your buddy there work at a shop? Don't they have a scan tool you can plug in? Maybe they have mitchell on-demand so you can follow the diagnostic procedures?

[LTb1ow]

Thats the dilemma, we did use his scanner and it could not read the ABS.

[BonzoHansen]

what is the troubleshooting chart for that? there is one I'm sure. Check for opens, maybe power at certain leads, etc.

[LTb1ow]

Yea, we never got that deep into. Its just weird that this all happened after I forgot to plug in the TCS motor in... I did nothing else... so like why would the ABS decide to play games now?

[BonzoHansen]

did you check all the fuses?

[LTb1ow]

Yup. And as stated, I did not unwire the TCS or anything. We plugged the motor back in, reset the PCM and what not, and still, nada.

[BonzoHansen]

I'd suggest digging into the correct service manual or mitchell o/d. You can do it.

Follow the directions. The tech tools tell you where to start, not necessarily what is wrong. It really may be as simple as "test for ground at A, test for power at B, if good and no signal, replace module"

[LTb1ow]

Ok, I have a haynes manual, I will dig that out and see if it helps at all.

Ebay you said though?

[JerzLT1]

it sounds like a bad ground to me or something like it. as far as i know your TCS and Airbags have nothing to do with each other. i would go back and make sure you didnt pull off any grounds when you were fooling around with the throttle cable under the dash. is this your daily driver?

[LTb1ow]

Kinda ish.

[JerzLT1]

and you dont want to pull out the ABS right?

[LTb1ow]

I wouldn't really care, but the car stays at my parents house and on their policy so they say no.

[BonzoHansen]

Ok, I have a haynes manual, I will dig that out and see if it helps at all.

Ebay you said though?

No, not haynes, you need a real shop manual. See if you buddy has mitchell on demand or mitchell books at the shop.

[91chevywt]

GM "Trouble Trees" are excellent at diagnosing problems like this. Finding the correct troubleshooting procedure will be a big help, and probably help you narrow the problem down big time. If you find a GM or equivelant manual would be good...haynes or chilton can't get you out of this problem.

[sweetbmxrider]

yeah i will do some more research. i have a gut feeling its a ground issue but i would rather follow a diagnostic chart. sucks i am leaving friday. i will try to get stuff figured out before then.

[LTb1ow]

No problem man, its not like its not drivable, I just wanna get this fixed.

[LTb1ow]

Ok, checked the voltage, 14.4 at idle.

Dunno if that helps.

[NastyEllEssWon]

you do know that the rear abs brakes and traction control use the same wheel speed ring/sensor setup?




if you delete the traction control your going to have to swap over to a 3 channel abs system which uses a reluctor ring in the rear to control the abs.

[LTb1ow]

I did not delete traction control, all I did was remove the motor part.

Which basically just pushes your pedal up when low traction is found. It was just a motor, and I did not cut anything. Just unplugged it.

So yea.

[NastyEllEssWon]

i could see if i can get my hands on a dealer scanner before you bring it there. let me talk to my guy before you do anything drastic

msd was in the car before he deleted the traction control. that has since caused said issues.





i was misinformed mr. nomercy

[LTb1ow]

Yup.

All I did was unplug the motor and start the car, forgetting to plug it in. FML.

[NastyEllEssWon]

maybe your fried something when you started it with the motor...



did you check the wire connectors for corrosion at all? the ones you unplugged? check for shorts?

[LTb1ow]

Its just a plug harness. Like an injector thing, simple. The whole thing is driving me nuts.

[NastyEllEssWon]

i understand that but did you check around for shorts or breaks in the wires?

maybe the vibration from the start up is causing a short to wiggle and make the lights flicker

[LTb1ow]

It could be that, but since this only started right after starting the car with the ASR motor unhooked I don't think so.

[NastyEllEssWon]

It could be that, but since this only started right after starting the car with the ASR motor unhooked I don't think so.




maybe you broke the pins in the connectors

[LTb1ow]

Nope, bigish wires, 12-14 range, so no way I broke em, and theres only two.

[HeadlessNorseman]

Well I am kinda giving serious thought to bringing it to a dealer. But I just don't want to leave my car with anyone :(

Also, I am not sure what kinda scanner Adam has but it looked pretty professional, I am wondering if a dealer or other shop would be able to do anything more than see that its not communication and say oh well.

Goto pinebelt, ask for Dan, tell him I sent you. Hes my uncle. You wont get much or any of a discount, but hes very professional and wont mess your car up

[LTb1ow]

It may come to that.

[Formulalt1]

You do know that the ABS and air bags share the same harness ground location, right?. Its a stud ground located on the passenger side fender well and if its a grounding issue you will most likely hear a unusual clicking (not the normal relay one click of it getting tripped) coming from the driver side fuse box relays.

[Mike]

You do know that the ABS and air bags share the same harness ground location, right?. Its a stud ground located on the passenger side fender well and if its a grounding issue you will most likely hear a unusual clicking (not the normal relay one click of it getting tripped) coming from the driver side fuse box relays.

that. do it.

btw, if you made abs go away.......how would they know :shifty:

[LTb1ow]

Eh, its just more of they asked me not too....

And I will check that ground out, is it inside the fender well?

[sweetbmxrider]

no i believe its the one by the battery positive junction, its the stud by the p/s

[Mike]

yeah the junction right next to the fuse boxes i believe

[sweetbmxrider]

our fuses are on the driver side.

[LTb1ow]

Oh, the big main one on the passenger side?

I will check it out.

[Mike]

our fuses are on the driver side.

so are mine, i misread the original post thought he said driver side

[sweetbmxrider]

so are mine, i misread the original post thought he said driver side

ah got ya

[Formulalt1]

no i believe its the one by the battery positive junction, its the stud by the p/s

That would be the one.

[LTb1ow]

Does that stud also go through the fender wall? Like are there wires connected to the underside of it?

[Formulalt1]

http://shbox.com/1/fusible.jpg . The one in the first half of the pic at the top right. The gold one with 3 ground lugs I believe. When I swapped my engine the first time and I was rewiring everything up I forgot to reconnect those three ground wires to that plug cause they kinda retracted and hid themself inside the loom and I didn't notice them at first. Anyway, I got a ABS light and airbag light intermittenly either flashing or staying solid and alot of clicking going on from the driver side relays, just thought I would mention that.

[LTb1ow]

Yup, I was screwing with that when hooked the juice up. I shall check it out.

[LTb1ow]

Thanks a lot guys!


Really appreciate the continued support. Turns out it was a loose ground on that ground post. The post had the nut on top but also the stud held down a pair of grounds and the stud itself was loose.

Thanks again!

[sweetbmxrider]

you buy beer, NOW!

[LTb1ow]

Aha. Yea I owe you a few now

[Formulalt1]

No problem. I am glad I was able to help. Good luck.

[Mike]

sweet easy fixes ftw, good thing you didn't give up and take it to the dealer to pay for something that simple

[LTb1ow]

Haha yea... although I am curious to see how a dealer mech. would like the 107LSA. :twisted:

[BonzoHansen]

Thanks a lot guys!


Really appreciate the continued support. Turns out it was a loose ground on that ground post. The post had the nut on top but also the stud held down a pair of grounds and the stud itself was loose.

Thanks again!

Did that help your charging issue too?

[LTb1ow]

Not sure, I have yet to drive it anywhere, no gas money.