Electrical Gremlins? ABS A/C etc - ZR-1 Net Registry Forums

emmvette · 08-26-2013

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 · 08-26-2013

Quote:

Originally Posted by emmvette

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 · 08-26-2013

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 · 08-26-2013

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 · 08-26-2013

Quote:

Originally Posted by 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.

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 · 08-26-2013

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 · 08-26-2013

Quote:

Originally Posted by emmvette

...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.

emmvette · 08-26-2013

Quote:

Originally Posted by scottfab

Here are where grounds are. The "Cs" are connectors and the "Gs" are the grounds.
http://zr1.net/forum/picture.php?pic...547239&thumb=1

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

scottfab · 08-26-2013

Quote:

Originally Posted by emmvette

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 · 08-26-2013

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

08-26-2013	#1
emmvette Join Date: Jul 2013 Location: Central Iowa Posts: 190	Electrical Gremlins? ABS A/C etc 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. __________________ [CENTER][SIZE=4][COLOR=red]1990 ZR-1 Red / Red[/COLOR][/SIZE][/CENTER]

08-26-2013	#4
Franke Join Date: May 2013 Location: Beaver, PA Posts: 516	Re: Electrical Gremlins? ABS A/C etc 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.

08-26-2013	#6
Franke Join Date: May 2013 Location: Beaver, PA Posts: 516	Re: Electrical Gremlins? ABS A/C etc 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?

08-26-2013	#10
gbrtng Join Date: Feb 2006 Location: San Antonio area Posts: 1,179	Re: Electrical Gremlins? ABS A/C etc 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 __________________ “Buy the best example of what you want, and pay whatever it takes. That way, you cry only once.” ~ Bruce Meyer

08-26-2013	#3
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: Electrical Gremlins? ABS A/C etc 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. __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V Last edited by GOLDCYLON; 08-26-2013 at 03:23 PM.