The master brake unit has gone out on our '90 Bonneville - again. Spring of '03 when it went out the first time I picked one up from a junkyard, came out of a Cadillac, I understand that system was only used from '88-'90.

Rebuilt units are expensive. I'm not sure I want to trust another JY unit. Frankly, I'm not sure I want to fix the car. But, given those options, how would converting it over to non-ABS power brakes do? Would the "Brake" and "Antilock" lights stay on constantly? Are the brake lines completely different so I'd have to change that all out if I went that way?

Anyone else dealt with this?

I'm dealing with poor braking performance and plan to address this in the spring. I have a parts car and intend on swapping the antilock assembly. If it still sucks then I'm converting to a normal vacuum assisted system. Haven't done much research myself but here'* some information on a conversion in a Trofeo which uses the same Teves system that is found in our cars:

http://www.bonnevilleclub.com/forum/...ic.php?t=34481

More than likely, your Antilock light will illuminate but you should wire the Brake light correctly to function as a working warning light. I've removed the Antilock bulb from my cluster... no more light.

About a year after replacing the master, it started a weird pedal thing where it would slowly move toward the floor as you applied it, then would stop doing that and hold close to the floor. Bleeding/flushing the system helped a little, but it still did it from time to time. It pretty much stopped doing that a couple of months ago. Now, it acts like a regular power brake system with the booster out - pedal is nice & hard, but it won't stop the car.

I did what I should have done before posting and went out to compare it to our '91 LE. I see the different number of brake lines, also looks like the proportioning valve is built into the master (unlike the f-body system mentioned in the thread you linked). Wonder if it would work to cap off one of the rear ports and hook up the current ABS rear line to just one port of the "regular" master.

I think I'd go with another ABS master before going through the conversion hassle. We'll see what the auto parts recycler quotes for another one.

If the brakes are not going to the floor you probably need a pump motor.
Is the light staying on?
I have a JY complete Teves unit only I had to cut the plunger bar in my haste to get it out of the car through the firewall.

Yes, both the "Brake" and "Antilock" lights stay on constantly.

I tripped over the removed unit for about 6 months before I finally tossed it. Oh, the things you wish you'd hung onto . . .

Its probably that round black motor not pumping pressure. Thats why its not stopping and the lights are staying on.
I notice when I first start up the lights stay on until the motor pumps enough pressure then they go out.

Since we've had the car (Oct 2000), the Brake and Anti-Lock lights would stay on for several seconds, typically while backing out of the driveway. Same with both the original unit and this replacement.

Tonight I pulled the power connector off of the motor and checked for voltage. None with the ignition off, 12v with it on. I plugged it back in, and the motor started. "Alright!" I thought. Got in, started it up, and the Brake & Anti-Lock lights went off before I got my seatbelt fastened. As I backed out of the garage, the first time I hit the brake pedal they came back on, but the brakes worked. I took it around the block, and by the 3rd stop, the pedal was hard again. Back in the garage, went through the disconnect routine again, nothing. With ignition on and power connector connected, I disconnected the connector above that (a pressure transducer looking thing), and the motor started in kind of a stuttering fashion, and I heard a relay clicking rapidly on the firewall. As I fiddled with the harnesses going from the brake unit to the firewall, it seemed to run and stop coincident with moving the harness. It finally built up pressure and turned off. However, when starting it up again, the lights stayed lit, and the brakes didn't have the power or reserve that it had before.

Back in the garage, tried fiddling with connectors & harness & relays, now it isn't running at all. I gave up before trying to jumper the power from the relay. Actually, didn't check for voltage again (probably should have done that, but it was getting late).

So, that'* where it'* at so far. Haven't heard from my used parts specialist; emailed him, he hasn't answered, guess I'll give him a call tomorrow.

If you going to look for a used replacement, i thought i'd just let you know that the teves II system was used on 1988-1990 MY bonnevilles with ABS. 1991 bonnevilles recieved a Vacuum Boosted Braking system.

The brakes on my car failed on me a few times. The motor would work intermittently and the brake and abs lights would come on, 3 stops later the brakes would fail. Scary stuff. It ended up being the brushes in the electric pump motor that wore out. Disassemble, insert brushes from hand drill, reassemble, drive away. Ive also got a spare unit incase mine dies again though, just in case.

thats good to know you could change the brushes on the motor. Prabably like a starter.
Did you fabricate some from a hand drill?
Also before you do anything you would do well to disconnect and clean all electrical connectors to the teves as well as swap out the relay with another one.