Electrical Gremlins? ABS A/C etc

[emmvette]

1990 ZR-1:

Last weekend my ABS light came on and the ABS system went off. Confirmed it on corner #3 of autocross. What's all that smoke under your tires, mister? Oh, that's my ABS not working. It was good to re-learn to brake without the ABS and I was fine. Codes 71 & 76 which are the EBCM and the lateral accelerometer are what I found with the paperclip.

Also had the INFL RES. Light. I fixed that (it was the RF mount) and then reset that code and the ABS codes and took a quick drive. The ABS light came back on and I confirmed it is not functioning.

I removed the tray in the rear hatch and looked around - verified the EBCM is connected.

The night before that happened, I noticed the radio lights wouldn't shut off. I opened and closed the doors (both) a few times and that self corrected - for now.

Then I noticed this weekend the A/C wouldn't work - the whole group of controls does nothing when you touch them.

And I also noticed the little cluster above the A/C controls does not work - the fuel and trip meter buttons. On my digital dash it shows 0 for the fuel mileage and won't change between instantaneous and average anymore. Basically none of the buttons work.

A few times I've also had the selective ride control indicator light come on. Each time it has gone back off within a few seconds or minutes. Personally, I can't tell if the selector works, I can't feel a difference between modes. I understand this isn't uncommon.

Have you guys seen similar issues? Any thoughts on if these are all related? Kind of seems like I may have a ground issue or similar.
I like wrenching, but to be honest I'm not a good electrical troubleshooter.

[scottfab]

1990 ZR-1:

... snip...
Have you guys seen similar issues? Any thoughts on if these are all related? Kind of seems like I may have a ground issue or similar.
I like wrenching, but to be honest I'm not a good electrical troubleshooter.

I think you're on to it. Grounds.
Start with the ones at the top of the bell housing.
With some finesse you can get a ratchet with long extensions
in there from under the car. Loosen the re-tighten.
This may give you temporary relief of the issues.
If it does then the permanent fix is painful. You'll need
to remove the bolts and scuff up each electrical lug then
reassemble with dielectric grease.
When mine acted up I had about half of the symptoms you list.

[GOLDCYLON]

Before you do anything unplug the battery wait a couple of minutes and plug it back in. The accelometer is right below the power key behind the radio surround. Grounds maybe but you have a whole host of electrical gremlins going on there.

[Franke]

According to the service manual the HVAC control head, HVAC programmer, Selective ride control, and a bunch of other circuits are tied to ground at G202 and G201. Location for G201 is shown at the drivers door - hinge side. Location for G202 is at the passenger door hinge area. It doesn't go into detail exactly where.

[emmvette]

According to the service manual the HVAC control head, HVAC programmer, Selective ride control, and a bunch of other circuits are tied to ground at G202 and G201. Location for G201 is shown at the drivers door - hinge side. Location for G202 is at the passenger door hinge area. It doesn't go into detail exactly where.

Thanks, Franke! I'll check those. The accelerometer seems to function, but does not read the correct values with a multimeter. I'll get a used one coming my way.

I have the service manuals but am struggling to find where they show the grounds are located at. If anybody can provide more detail on the G201 & G202 Franke mentioned, please let me know. I'd love to double check them.

Did find one "ground" loose on the back of the instrument panel / control center. Tightening it took care of the trip meter/gas mileage buttons not working. Fuse took care of the A/C (I kind of figured I'd find that). I did look at them the other day, it must have just happened in the day or two.

[Franke]

Good for you that you found some of the problems. I'll bet the grounds are inside the kick panel area - just a guess. 1 caution when working on the ABS be sure and note the peliminary diag checks in section 5E of the manual. Also, according to the manual, code 71 needs to be cleared before code 76 as 71 may be causing 76. Are you sure the EBCM is ok?

[scottfab]

...snip...

I have the service manuals but am struggling to find where they show the grounds are located at. If anybody can provide more detail on the G201 & G202 Franke mentioned, please let me know. I'd love to double check them.

...snip...
.

Here are where grounds are. The "Cs" are connectors and the "Gs" are the grounds.
http://zr1.net/forum/picture.php?albumid=199&pictureid=2330

[emmvette]

Here are where grounds are. The "Cs" are connectors and the "Gs" are the grounds.
http://zr1.net/forum/picture.php?pictureid=2330&albumid=199&dl=1377547239&thumb=1

Edited - I figured out your post. Was having trouble seeing the prints.

[scottfab]

Edited - I figured out your post. Was having trouble seeing the prints.

The first link I used was to the thumbnail. Not very useful.
Good luck on the G201 and G202. Let us know if that was it
else we'll be glad to help isolate to the root cause.

[gbrtng]

Eric:

A suggestion: I've found that multiple unrelated electrical gremlins usually center around the two control modules - the ECM and the BCM. Yours seem to be BCM related, so before you go too much farther than the grounds check, consider swapping in a known good BCM. At least that's what I'd do next.

Cheers,
Glenn

[emmvette]

I think about everything is sorted out now - except the A/C. Keeps blowing fuses and can't find where the problem is.

[gbrtng]

Check the resistance of the AC compressor coil first - should be about 3.4 ohms.
When that fuse blows, you get SYS messages and not much else works either.

[batchman]

I will say that I've found a few things "autocross related" worth mentioning:

- door switches will indicate "door open" in spirited cornering ;)
- doesn't take much stress for battery connection to be "iffy" and give intermittent "sys"
- hub play can lead to ABS light

I always thought "I never kick into ABS", learned different when one day the only spare hub I had was from the '88. Boy did I ever make some flat spots that day.

Sounds like you're on the right track though.

Cheers,
- Jeff

[emmvette]

Check the resistance of the AC compressor coil first - should be about 3.4 ohms.
When that fuse blows, you get SYS messages and not much else works either.

I haven't done this yet; guess its time to pull the plenum. Will the coil cause the fuse to blow?

By the way, here's a pic from the other weekend. It was kind of funny, somebody took this pic right as I realized my ABS was gone - it looks like I slid a little right as this was taken - I'm a long ways from the near side cone!

ABS or not, I had a great time and the car performed very well. Now the driver - lots to learn and having fun doing it!

http://i577.photobucket.com/albums/ss217/emmvette/ZR-1/AutoXAnkeny1_zpsc9ea73c1.jpg

[gbrtng]

Check the resistance of the AC compressor coil first - should be about 3.4 ohms.
When that fuse blows, you get SYS messages and not much else works either.

More to the story - I fought an intermittent AC fuse blow condition on Mary's 91 L98 - drove me nuts for several years - turned out to be a bad clutch bearing and the clutch finally ate into the clutch coil causing a dead short to ground.
Replacing the bearing and coil fixed the problem. Did not have to replace the compressor assembly at a much higher cost - phew ...