how2disable ABS on 91 chev caprice (its pushing my foot off!)

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Oct 6, 2014
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Location
Minnesota
Short version, if I need to disable the ABS system in a 1991 Chevy Caprice, do I just pull a specific fuse or is there anything else to be concerned about?


Long version as to why... i'm having a wierd problem where the ABS keeps pushing my foot off of the brake, and I am currently moderately injured (I have no use of my left arm at all) making it very difficult to do whats probably the "proper" repair even if that's not very big so i'm just kicking it down the road.

People can respond on the proper repair for when I get to it (maybe after six months more physical therapy) but I just want to shut off ABS entirely for now. I've driven without ABS my entire life on all my other cars so i'm not worried especially not in the summer, my "manual ABS" has always got me thru every winter as my other vehicles lack it.


Longer story is 1991 chevy caprice classic, 5.0L V8, with what I think is the 3 channel ABS system (the cadillac had a 4 channel I believe, this is a 3 channel) and 180k miles.

A few thousand miles ago I started periodically having the car try to push my foot up whenever I had it on the brake and the vehicle was completely stopped. This was very intermittent (only once in awhile) and would only happen one out of a number of stops. It would also stop if I shut the car off then turned back on, or often if I just rolled forward two feet or so. (i'm guessing there might be gunk in the sensors somewhere)

This has gotten more and more often so that now it happens literally on nearly every stop, and the pushing back has gotten more aggressive. It will start making the car move forward a few feet if it's on the slightest bit of a hill so now I have to do something, it's gone from annoyance to "i'm wondering when this will make me nose out in traffic at a stop light soon". Generally stomping my foot down HARD seems to keep me in place so far but I can't ignore it.

No I cant afford to take it to anyone. Coronavirus took my job. Trying to not be homeless.
 
On that year model pushing the parking brake one click (or until the brake light activates on the dash) should also disable it.
 
Originally Posted by Jethro_Bob
On that year model pushing the parking brake one click (or until the brake light activates on the dash) should also disable it.

+1
 
Okay, i'll just pull the fuse for now. I was hoping and assuming it could just fail-safe.


Though if anyone has ideas on what might be causing this problem for eventual consideration i'm still all ears so i'm hoping someone will respond when they can so I can know what I have to do later.
smile.gif
 
Looks like you've got a Bosch 2U ABS system

On a typical General Motors application with a Bosch 2U ABS system (1990-94 fullsize rear-wheel drive passenger car), for example, codes can be accessed manually by grounding terminal "H" on the ALDL connector, then counting flashes of the ABS lamp. On these systems, flash codes repeat three times. Codes will stay in memory 50 ignition cycles. But to clear codes, you need a scan tool.

On ABS systems that provide manual flash codes (such as Bosch 2E, 2S, 2U and 3, Kelsey-Hayes RWAL and 4WAL, and ITT Teves Mark 2), you do not need a scan tool but using one reduces the chance of misreading a code.

http://www.troublecodes.net/GM/

The ABS brake system has separate diagnostics. Here's how to do the ABS system diagnostic test:

Turn the ign switch to the "ON" position. Jump terminal "H" to terminal "A" of the DLC (AKA ALDL) and count the number of "ANTILOCK" lamp flashes. The terminals must be jumped for a few seconds before the DTC (Diagnostic Trouble Code) will begin to flash. Here's an example: if the lamp flashes twice once, then that indicates DTC 21 which is listed as "Right Front Wheel Speed Sensor or Circuit Open (Static)".

If the ABS system is working properly then codes 12, 13, 14 or 15 will display depending on whether 2WD/4WD & whether brake pedal is released/applied.

Here's the procedure for clearing ABS codes:
1. Turn the ign switch to the "ON" position.
2. Use a jumper wire to ground DLC terminal "H" to "A" for 2 seconds.
3. Remove the jumper wire for 1 second.
4. Repeat the grounding for 2 seconds.
5. An indication of success is when the "ANTILOCK" and "BRAKE" lamps turn on and then turn off

IMO, start simple

When your up to it, pull and inspect all 3 sensors (one at each front wheel, one at the rear diff), clean off metal filings and goo
Inspect tone rings

Go from there
 
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