Strange Sound ABS (Post Updated)

[RobertoGonzalez]

Hello folks! Greetings. My 1991 Volvo 960 has a strange sound in the break pedal. I guess.
The car has an automatic transmission, and after I change the gear lever from P to D, and the car starts to move slowly, a strange sound appears. It appears 2 or 3 seconds after the car starts to move.
That sound, it also appears after I change positions from P to R. The thing is that the sound do not appears every time, the car has to be in park for at least 15 or 20 minutes with the engine turned off, because if not, if I am driving normally and I change gears from D to R, or if I put P and then D again and I have been driving for a while, that sound does not appears.

If I put my feet just a little bit in the pedal break when the sound appears, I feel a little vibration. It is very, very subtle. Also, if I do that, to put my feet in the pedal break when the sound appears, the sound sounds louder. I really don’t know how to explain better this issue. I have uploaded a short clip, maybe it helps to explain better.

Any comments?

Thanks!

[CIK7]

Hello folks! Greetings. My 1991 Volvo 960 has a strange sound in the break pedal. I guess.
The car has an automatic transmission, and after I change the gear lever from P to D, and the car starts to move slowly, a strange sound appears. It appears 2 or 3 seconds after the car starts to move.
That sound, it also appears after I change positions from P to R. The thing is that the sound do not appears every time, the car has to be in park for at least 15 or 20 minutes with the engine turned off, because if not, if I am driving normally and I change gears from D to R, or if I put P and then D again and I have been driving for a while, that sound does not appears.

If I put my feet just a little bit in the pedal break when the sound appears, I feel a little vibration. It is very, very subtle. Also, if I do that, to put my feet in the pedal break when the sound appears, the sound sounds louder. I really don’t know how to explain better this issue. I have uploaded a short clip, maybe it helps to explain better.

Any comments?

Thanks!

your brake pads or rotors or both might need replacing.

[RobertoGonzalez]

Hello folks! Greetings. My 1991 Volvo 960 has a strange sound in the break pedal. I guess.
The car has an automatic transmission...

your brake pads or rotors or both might need replacing.

Hello! Thanks for your reply. I’ve been told that the problem is in the ABS system. When I hit the brakes to make an emergency stop, I feel the pedal vibrating (they say that it’s normal when the ABS is active) and the sound it multiplies by 10000 times louder. When I push the brakes normally, it does not sound.
I didn’t do that test before, it was the idea of ​​a mechanic, so that it’s why I didn’t explain better before. In few more days they are going to check the system, open and see if maybe there is something wrong with some pieces of the ABS system. Disarm and check.

If you have any comments or suggestions, please let me know, everything helps and it’s appreciate.

Regards.

[lummert]

ABS tone rings on the front hubs may need cleaning to remove rust. You need to remove the front rotors to check the tone rings. Temporary test would be to unplug the front ABS sensors, which are found on the inner fenders under the hood (bonnet), to disable ABS then test drive to check if the car still has the issue.

[RobertoGonzalez]

ABS tone rings on the front hubs may need cleaning to remove rust. You need to remove the front rotors to check the tone rings. Temporary test would be to unplug the front ABS sensors, which are found on the inner fenders under the hood (bonnet), to disable ABS then test drive to check if the car still has the issue.

Hello! Thanks for the answer. I cleaned the ABS rings, I tested and the sound was still there. Then, I disabled the sensors and the sound disappeared. The sound that appears when the car starts to move (the initial movement from P to D and without pushing the brakes) and the sound that comes when you hit the brakes and the ABS system is active, those sounds disappeared.

The mechanic told me that it was going to be hard to find someone who can open the box of the ABS system and repair it, see the valves and all that. The car stops good, there’s nothing bad with the performance in that matter, but it’s the sound when you hit the brakes or when the car just star to move (after being park) that is weird.

Thanks again for your reply.

Regards.