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tbonz
10-12-2010, 01:28 PM
Hi guys,

I've read the posts about ABS problems, this just started happening last week to my 91 sc. Both lights illuminate, pedal is hard, brakes aren't working. My brother works on the car regularly, and says it seems like the relay isn't being triggered, possibly not getting juice. The brown abs relay was changed yesterday and didn't resolve the issue.

A footnote,some unrelated work was done a couple of weeks ago(timing chain cover had a crack in it), and when complete the entire engine compartment was cleaned. The problem started after the cleaning, can this be related?

Are there any symptoms to a bad pressure switch?

Thanks for any help!


Todd

Mike8675309
10-12-2010, 01:54 PM
Brake Light is triggered by a couple things unrelated to the ABS.
In other words if you have an ABS light, that doesn't mean you will have a brake light. And if you have a brake light you may not have an abs light (though usually you will).

Basics. Check that the fluid is full. Then check around the master cylinder and disconnect and re-connect the connector to the hydraulic pump and the connectors for the pressure sensor and level sensor.

RalphP
10-12-2010, 04:06 PM
Also, remove the ground wire under the screw on the front of the ABS control valve, polish the aluminum of the valve and the washer, and reconnect.

Now - with someone inside, have them turn the ignition on while you listen to the motor. Does it run at all? If not, it's time to start seeing if there's power getting to it or not. If not, disconnect the pressure switch and short the contacts together. If the motor then runs, it's a bad pressure switch. If not, that's not it (or not all of it.)

There's also a second ABS relay besides the brown one. In Sweetie's car, it's the left most IIRC (the brown one is the right one) as I look over the radiator to the motor (i.e., the one furthest to the right of the car itself). Duffy Floyd's great treatise on the Teves Mk II ABS tell you which relay is which in the three relay bundle from year to year.

It's worth a look see, I do think.

RwP

92supercoug
10-12-2010, 05:10 PM
okay so i'm having the same problem in my car and i'm wondering if its the relay to because the motor wont run with the key on but if i disconnect the battery and reconnect it and turn the key on it will start and run and once it shuts off it wont start again until u disconnect and reconnect the battery again.

Mike8675309
10-12-2010, 05:55 PM
If you haven't yet found this link, you should be reading it:
http://www.35thatr.org/Tips/ABS.htm

the-big-e
10-12-2010, 07:50 PM
Try cleaning the contacts on the relay first (this has solved an ABS problem on two of my SCs)....

If that doesn't solve your problem, (if I remember correctly) then you can jump the plug to see if the pump motor runs.....

Look at the male terminals on the relay....

You will see three large and two small terminals....

You want to run your jumper wire between where the two small terminals go into the plug.....

tbonz
10-13-2010, 12:43 PM
If the motor then runs, it's a bad pressure switch

Jumped the wires and the pump does run. The blue and red wire that is controlled by the relay, does something turn on and off the ground?

We got a code #11(controller) is this consistent with the pressure switch?

Thanks, I want to be sure before buying any parts.


Todd

Brad2296
10-14-2010, 01:33 AM
The pressure switch is not as hard as it seems to change. "The-Big-E" is where I got mine from when mine went out. You will need the following tools...

1/2 drive 36MM deep socket
1/2 drive 3" extension
1/2 swivel
1/2 drive 10" extension.

Connect the socket/extensions as listed, then to a socket wrench, do not use air tools. Put just the socket on the old switch first, then put on your 3" jig and take it out. You'll only be able to make about 1/4 turns at a time, but it's the easiest way to do it, unless you remove the whole unit. Then reverse the procedure to put it back in.

Make sure you pump your brakes before removing the switch, there is pressure behind it!

tbonz
10-14-2010, 12:08 PM
Thanks Brad!

I am going to order the pressure switch later today, I hope that is the problem, the code 11 had me a little confused.

Thanks again!


Todd

tbonz
10-17-2010, 12:37 PM
Hey Guys,

my pressure switch will be in tomorrow..... today my brother had the car out for a bit, and noticed that the 2 brake lights went out and brakes functioned properly when he made a hard left turn, and later went back on when making a hard right. Fluid is full to specs, is there anything else that might cause this symptom?

thanks again!


Todd

the-big-e
10-17-2010, 01:16 PM
Did you try cleaning the contacts on the relay?

tbonz
10-17-2010, 08:09 PM
Yep contacts cleaned, didn't make a difference.
Thanks! Any other ideas?

tbonz
10-21-2010, 01:59 PM
Hey guys,

Progress has been made, pressure switch is finally changed. Now sometimes when pushing the brakes the lights come on but go right off. The pedal feels good even when lights go on, so my question is, is it possible that there is air in the lines, and they need to be bled? If they do, is the process straight forward, and/or documented here anywhere?

Thanks for all the help and info you have provided!


Todd

tbonz
10-21-2010, 07:39 PM
Last question...everything seems to be working perfectly after bleeding.

Pedal feels good, lights aren't going on at all under regular use, tested/drove for over an hour high and low speeds without any issue. The only way I have gotten the lights to quickly flick on is by pumping the brakes...since I have never pumped them during regular use, I am not sure if that would normally cause the antilock light to flash on. Even when the light flashed on due to pumping, the pedal felt fine. Is this normal behavior or an indicator of something else?

Thanks!

Todd

the-big-e
10-21-2010, 07:58 PM
Flashing / flickering lights are a classic sign of an accumulator going bad.....

tbonz
10-22-2010, 12:04 AM
Thanks for responding big-e!
Damn really? Maybe I shouldn't have said "flick", they didn't repeatedly flicker. They only illuminated briefly (1 illumination for a split second) if I pumped the pedal repeatedly. The result was able to be produced any time I pumped the brake pedal repeatedly like 3-5 times. Pedal also felt fine even when the lights did illuminate for the split second. Other than that they were fine under all braking situations, and the lights did not illuminate under any other braking condition.
Drove stop and go, steep hills, high speed to full braking, all performed perfectly. ABS functioned properly as well, felt like it did before any of this started acting up.

the-big-e
10-22-2010, 04:58 PM
Might as well go ahead and replace the accumulator.....

Or at least have one readily available when it finally goes out....:p