ABS Not Working after Installing new gears.

Dan Fahey · 10-15-2013, 02:11 PM

Preparing my 1994 Caprice wagon for towing.
Just had 3.08's Installed which originally had 2.56's.
The 3.08's were from my 95 Impala SS.

After installation Re-flashed the PCM for the 3.08's gears.
Now the ABS INOP light is coming on.

Tested the Front Wheel Sensors and Pinion Sensor on the Pinion housing.
They were all working properly. The Car has new 94 ABS Brain.

When starting up the engine ABS light reads the Brain and goes off.
Travel about 30 seconds the ABS INOP Light comes on.

Attached new SnapOn Test tool to check everything out.

Results:
The Speedometer is reading the same speed as the Front Wheels
The Rear Sensor was reading about 5 mph less.

Have TunerCat. How can this be corrected?

Dan

Ed Wright · 10-15-2013, 03:48 PM

Don't those have the ABS reluctor on the pinion? They are different for different gear ratios.

bob shirley · 10-15-2013, 04:29 PM

3.08 s need reluctor with 20 openings for abs to function

ss3011 · 10-15-2013, 04:49 PM

If the sensor was on the diff ring gear , it wouldn't matter what ratio you had. I think the ABS sensor reads off the reluctor that is on the transmission output shaft. Try reloading the old ratio and see if the ABS works. This all depends where the signal for the ABS comes from, and where the reprogrammer recalculates it.

Dan Fahey · 10-15-2013, 05:49 PM

Quote:

Originally Posted by bob shirley

3.08 s need reluctor with 20 openings for abs to function

YUP..You are right...forgot that.

The PCM measures the Reluctor on the Tail Shaft Housing.
The ABS on the Tail housing.

Looks like they installed the wrong one on the Pinion.

Thanks

D

Dan Fahey · 10-16-2013, 12:11 PM

Problem solved.

Just spoke to the Mechanics that Installed the Gears.
They though it was a 3.73 gear set instead of 3.08's.
Used a 3.73 Reluctor.

FWIW going through the entire ABS system with another Mechanic.
Learned a lot about them.

Here are some links I used to study and troubleshoot the issue.
I learned to read Engine or ABS Codes without a Scanner.

http://www.troublecodes.net/gm/
http://www.gmtuners.com/OBD1_DTC.htm
http://www.goldsswagon.com/ABS/Bosch...%20Systems.htm

Thank you all for the help..!!

Dan

ss3011 · 10-16-2013, 01:21 PM

Glad you were able to figure it out. Where is the reluctor located, Differential, or Transmission ?

10-15-2013, 02:11 PM	#1
Dan Fahey VIP Member Join Date: Oct 2008 Posts: 2,128 Likes: 1,084 Liked 184 Times in 113 Posts	ABS Not Working after Installing new gears. Preparing my 1994 Caprice wagon for towing. Just had 3.08's Installed which originally had 2.56's. The 3.08's were from my 95 Impala SS. After installation Re-flashed the PCM for the 3.08's gears. Now the ABS INOP light is coming on. Tested the Front Wheel Sensors and Pinion Sensor on the Pinion housing. They were all working properly. The Car has new 94 ABS Brain. When starting up the engine ABS light reads the Brain and goes off. Travel about 30 seconds the ABS INOP Light comes on. Attached new SnapOn Test tool to check everything out. Results: The Speedometer is reading the same speed as the Front Wheels The Rear Sensor was reading about 5 mph less. Have TunerCat. How can this be corrected? Dan

10-15-2013, 03:48 PM	#2
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 390 Times in 170 Posts	Re: ABS Not Working after Installing new gears. Don't those have the ABS reluctor on the pinion? They are different for different gear ratios. __________________ Ed Wright 4156 SS/JA

10-15-2013, 04:29 PM	#3
bob shirley Junior Member Join Date: Oct 2006 Location: las vegas Posts: 53 Likes: 0 Liked 0 Times in 0 Posts	Re: ABS Not Working after Installing new gears. 3.08 s need reluctor with 20 openings for abs to function

10-15-2013, 04:49 PM	#4
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: ABS Not Working after Installing new gears. If the sensor was on the diff ring gear , it wouldn't matter what ratio you had. I think the ABS sensor reads off the reluctor that is on the transmission output shaft. Try reloading the old ratio and see if the ABS works. This all depends where the signal for the ABS comes from, and where the reprogrammer recalculates it.

10-16-2013, 12:11 PM	#6
Dan Fahey VIP Member Join Date: Oct 2008 Posts: 2,128 Likes: 1,084 Liked 184 Times in 113 Posts	Re: ABS Not Working after Installing new gears. Problem solved. Just spoke to the Mechanics that Installed the Gears. They though it was a 3.73 gear set instead of 3.08's. Used a 3.73 Reluctor. FWIW going through the entire ABS system with another Mechanic. Learned a lot about them. Here are some links I used to study and troubleshoot the issue. I learned to read Engine or ABS Codes without a Scanner. http://www.troublecodes.net/gm/ http://www.gmtuners.com/OBD1_DTC.htm http://www.goldsswagon.com/ABS/Bosch...%20Systems.htm Thank you all for the help..!! Dan

10-16-2013, 01:21 PM	#7
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: ABS Not Working after Installing new gears. Glad you were able to figure it out. Where is the reluctor located, Differential, or Transmission ?