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Discussion Starter · #1 ·
I have a 1996 suburban 1500 that has the ABS light on. Its rare, but sometimes it turns off and I can tell the a difference
stopping on my gravel driveway at the rear end locking up or not locking up.
Where is the ABS wiring and sender located at the back?
Thank you in advance for the help

May everyone be safe out there
 

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Discussion Starter · #4 ·
I also have a check engine light on and went to the local parts store (auto zone). The gal checked with the plug in and said I need a 02 sensor. Stated nothing showed up on the ABS. Couldn't even tell me what 02 I needed out of the 4. What side, up stream or down stream. Waste of time.
GRRRRRRRRRRRRRR
 

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Codes mean nothing without the specific number
O2 sensor .....what ?
heater circuit?
slow response?
short in signal circuit
And about 15 other codes.
You need the number of the code.
That will tell you which and what .
Get your truck scanned by a pro.
 

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Where is the ABS wiring and sender located at the back?
That is an older system, no traction control stabilty etc
It has only 1 line to the rear brakes and has no sensor for the rears
The rear signal is generated by the vehicle speed sensor at the transmission. It then goes to the vehicle control module( computer ) , then to the ABS Hydraulic control unit
The front wheels have there own speed sensors. They are wired directly to the hydraulic brake control unit
 

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Discussion Starter · #7 ·
That is an older system, no traction control stabilty etc
It has only 1 line to the rear brakes and has no sensor for the rears
The rear signal is generated by the vehicle speed sensor at the transmission. It then goes to the vehicle control module( computer ) , then to the ABS Hydraulic control unit
The front wheels have there own speed sensors. They are wired directly to the hydraulic brake control unit
Thank you for the info. My speedometer still works with no problems. So the vss serves two functions from the one unit?
Would a replacement of the vss correct the problem? I will start with cleaning of the wire and see if that helps. The suburban is an old dog with 352k on the clock. I will get a pro readout on the codes.
Yesterday the ABS light went out for a while and then back on. One can tell a little difference in breaking on city streets.
I sure don't tailgate!

Thank you all for the help
 

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Discussion Starter · #9 ·
More likely the ABS hydraulic/electronic unit is the culprit
It also could be an issue with the instrument cluster
Could dirty hydraulic fluid make a problem? I will check the color tomorrow. My wounded 75 yr.old body only lets me
do a little work a day. I took a bad fall on the ice 3 weeks ago.
 

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It more likely a wiring issue, or a electronic component issue.
It could be a solder joint on the ABS module, the ECM (not as likely) or at the dash (instrument cluster)

Most of the time that I have seen a problem like yours, it was the ABS unit
 

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A majority of the time intermediate ABS is caused by junk on the sensor and/or a bad hub.
Pulling the wheel, caliper, then sensor to clean the sensor and check the hub for play is often enough to renew the sensor while your waiting for a new hub and/or sensor to arrive.

It is recommended you leave the sensor in then using soapy water and a brass detail brush($1) get all the crusty stuff away from the sensor before shooting the (torx) fastners with pentrating lubricant and letting them soak while you remove the wheel and caliper from the other side. Then go back and pull the sensor wiping debries away from the hole before installing the clean or new sensor.

A 1/8 turn tightening then 1/4 loosening then back to tightening then loosening often breaks things free easier then simply applying more torque and potentially breaking a bolt you really do not want to tap. A bit of pentrating lubricant and patience will make this easy job a easy job.

The 4wd hubs on these are easily replaced (compared to older units) and if there is any play then replacing the hub and wiping down the sensor may eliminate the ABS issue on its own.

I like a crust free chassis. A quick detail before working on things like this or doing regular maintance and keeping things clean will avoid catching a clump of dirt the next time you work on your ride. You also will not be covered in dirt and gunk after simple maintance.
 

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Discussion Starter · #12 ·
A majority of the time intermediate ABS is caused by junk on the sensor and/or a bad hub.
Pulling the wheel, caliper, then sensor to clean the sensor and check the hub for play is often enough to renew the sensor while your waiting for a new hub and/or sensor to arrive.

It is recommended you leave the sensor in then using soapy water and a brass detail brush($1) get all the crusty stuff away from the sensor before shooting the (torx) fastners with pentrating lubricant and letting them soak while you remove the wheel and caliper from the other side. Then go back and pull the sensor wiping debries away from the hole before installing the clean or new sensor.

A 1/8 turn tightening then 1/4 loosening then back to tightening then loosening often breaks things free easier then simply applying more torque and potentially breaking a bolt you really do not want to tap. A bit of pentrating lubricant and patience will make this easy job a easy job.

The 4wd hubs on these are easily replaced (compared to older units) and if there is any play then replacing the hub and wiping down the sensor may eliminate the ABS issue on its own.

I like a crust free chassis. A quick detail before working on things like this or doing regular maintance and keeping things clean will avoid catching a clump of dirt the next time you work on your ride. You also will not be covered in dirt and gunk after simple maintance.
Thank you for info on the old suburban. I will get at the front wheels as soon as weather will allow (still cold out).
One thing I have been told is that the deicer sprayed on the roads eats up the wiring. I try and drive off to the side of the spray area. Will be checking on a good reading this week. I found a trans guy who has a snap on reader. Hope it works out.

Thanks to all you good folks
It would be more fun to run the watercooled gun
 

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Discussion Starter · #14 ·
wheel speed sensors would set a code.OP states he has no codes IIRC
Having a code would make it a no brainer
Yesterday I had the truck scanned. I had a brake booster that was leaking air which was the problem of poor brakes.
I have two 0X sensors, one on each side, one up stream and one down stream that are showing bad.
The ABS problems: rt. front has an open circuit and a problem with power pump unit. Tomorrow I will go after the 0X
problems. The tranny guy loaned me the tool to remove the sensors. I will get them loose and return his tool. I will need to check the wiring with multi reader due to the scanner telling us one has a bad heater.
This all will depend on how I feel in the morning.
The brake booster was a pain in the ass to do. I don't fit under the dash at all, to fat !

Thanks again to a great bunch of guys
Watercooled................."If it ain't belt fed it ain't fun"
 

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The two O2 sensors are BOTH bad?

I would fix the air leak at the booster, clear codes and drive to see if they come back.That would be for lean codes or slow activity codes.
Now if the O2 had circuit codes, then yes ,likely they are failing.
R Fr wheel speed sensor circuit....yes, sounds like the sensor is bad.
What code number was the Control unit code.?

Aftermarket scanners may read codes that are false on an ABS version this old.
Post the code numbers for both.
If your guy used a tech1 or tech2 (GM scan tool) then post the codes
 
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