96 R ABS module - again

Post by **Clemens** » 11 Jun 2016, 06:45

So i boighz my R with abs and tracs light on. Cut the module open, found the main power supply solder joint cracked, soldered it and sealed evrrything with a rubber sealer for electronics.
Lights never came on till today. Now i have a permanent abs and tracs light right after startup. Where do i start looking for a mistake? Also, i need to mention that a?few weeks ago i had abs action on the front left or rear left wheel when braking hard and turning at the same time. Checked all wired and abs rings and they seemed alright. But of it were a sensor or a ring it would most likely not?illumnate the abs and tracs right after startup but after moving, right. Any ideas are welcome.

Post by **sleddriver** » 11 Jun 2016, 10:20

Same experience here. My repair would last for a year or so, then fail to the pump motor connectors. The last time it happened, I looked very closely at the failed joint and noticed that the solder joint failed right at the pad. Barely a mm in distance. So I sucked off the solder and noticed a very tiny pad...too small in my opinion, for such a large dia. pin/lead.

My solution was to remove additional material around the motor pins, exposing the copper layer underneath. Next I tinned this surface, before resoldering the joint. This provides a MUCH better connection to the circuit board that will withstand the vibration.

: Notice how the bottom left motor pin looks different that the right one. Also, note it's a bit blackened underneath. This is where it had separated from the PC board. The solder also appears "gritty". Don't remember leaving it like that.; ABS Module 003.JPG (142.32 KiB) Viewed 2167 times

: Here I've removed the top PCB layer, exposing more copper underneath.; ABS Module 008.JPG (168.59 KiB) Viewed 2167 times

Post by **abscate** » 11 Jun 2016, 13:06

Thats too much heat on that board. You need to be in good practice to pull this repair off.

Post by **sleddriver** » 11 Jun 2016, 15:52

I didn't overheat the board. The grey marks are not burn marks from a torch or flame.

What might look like it to you is actually from the small wire brush used in a Moto-Tool. It wasn't up to the job of removing the etch resist, thus I had to manually scrape it off.

Post by **Clemens** » 12 Jun 2016, 01:08

This is very interesting. Did you feel any strange behaviour from the pump or did just the lights come on?

@ moderators: i must have started two thredas accidentally. Sorry about that. Can you merge them?

Post by **sleddriver** » 12 Jun 2016, 10:46

I'm trying to remember when my ABS ever has engaged...in the 18yrs I've owned the car. No ice where I live, just heat & humidity. The brakes aren't touchy. It won't even skid, save for loose gravel.

Main code was "pump motor faulty".

Teddy1975 · Post by **Teddy1975** » 12 Jun 2016, 11:31

Don't need icy conditions for ABS to engage. Slam on the brakes so hard it locks up the wheels. ABS will/should kick in... But wait until there's noone behind you

Post by **sleddriver** » 12 Jun 2016, 11:55

ABS will only activate when the controller detects skidding. I've tried a panic stop from about 30mph. What happened was an immediate ALL STOP. No skidding at all. Write it off to new rubber!

I'm one of those who tries to swerve to avoid a potential collision, rather just slam on the brakes & pray. I've only lightly tapped a vehicle in front once...in 40 yrs of driving.

Post by **BEJinFbk** » 12 Jun 2016, 15:17

It activates when it senses a given differential in wheel RPM's.
Hit'em on gravel. If it's working, you'll know!

Post by **Clemens** » 16 Jun 2016, 01:21

Another thought on my issue: could it be the hydraulic block where the brake lines go to? How could that be diagnosed for sure.