Repairing ABS problems

Yes repairing ABS problems on older vehicles can be challenging. Recently I had a friend with a 95 Pontiac Bonneville STE that had a TCS or traction control light on, as well as the ABS warning light. My first problem was that this vehicle did not have OBD ii systems.

This meant that the latest generation of cheaper ABS scanners like the equus 3160 combination scan tool pictured to the right would not pull the code for me. They only work on vehicles 1996 and up.

The second problem was that I am not allowed to use shop equipment on personal, or friends vehicles. This left me without the ability to connect a scan tool and pull abs codes from the 95 Bonneville.

I decided to go into my online auto repair manuals and look for bulletins that referred to repairing ABS problems for a Pontiac Bonneville. I did find a bulletin to help me track down the problem.

Also note that this bulletin would apply to GM's counterparts such as the Buick LeSabre, Park Ave, Olds 98, and the Olds 88 from 1995 years and older.

Repairing GM ABS and TCS warning lights

So the components for the systems are shared for the most part. The fact that both the abs and traction control lights where both on was a hint at the problem.

The bulletin describes that the problem is corrosion in the shared ground splice for the pressure modulator valve. This junction is located very close to the electronic brake traction control module or EBTCM (better picture below).

Or if you purchase a car repair manual such as all data you will be able to find the component location in the wiring diagram section.

Again S129 is close to the electronic brake traction control module. In fact the splice itself is about 3 inches from the module assembly.

In my case the splice was covered with black tape and moisture had seeped in and caused a large amount of corrosion at this connection. This was causing intermittent operation of the abs pump motor.

Also note on the 95 Bonneville that I worked on it was necessary for me to remove the air cleaner assembly and the windshield washer bottle to gain complete access to the repair area.

On vehicles equipped with a automatic level control you will probably have to remove the compressor that services the system as well.

I cut out the heavily corroded splice and put in a new one using a standard brass splice crimp and generous amounts of solder.

Also before I started the repair I slid a over-sized piece of heat shrink wrap over the wires.

After the repair I positioned the shrink-wrap and melted it around the connection to prevent moisture from penetrating this area again.

Repairing ABS wiring on old cars

The most common failures will be from external damage to wheel speed sensors or corrosion on aging abs wiring.

Online repair manuals provide diagnostic charts for specific codes. They also provide component location diagrams for connectors and splices that help find the problem.

So you may not be able to follow the diagnostic charts in repairing ABS problems on specific models but it should be helpful in locating tcs and antilock brake system grounds and connectors.

These can be where the problem hides due to exposure to harsh environmental conditions and road-salt.

Before you continue on give this repairing abs problems page a

Electronic Brake Control Module

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