Brake Issue

[crobertson1]

Last night while were driving in the '93, the brake and ABS lights came on. The brake pedal feels real mushy and soft and travels a lot further. If you pump the pedal, it will feel better and the light will go off but also it will come back on in a minute or two. What's weird is, that when you push the brake pedal, the EGT gauge needle will jump and it's not working properly now either. It seems odd that they would be related. The front part of the brake fluid resevoir was low so I filled it up but that didn't help the symptoms.



Any ideas?

 

[cerberusiam]

Grounds, grounds, and more grounds. Anytime you see things like that its a good bet there is a bad connection somewhere.

 

[crobertson1]

Would a bad ground even effect the brake pedal though?

 

[PToombs]

Not the pedal, I bet there are 2 problems. Ground and brakes.

I bet the valve in the ABS unit stuck open, lets the pressure go to the accumulator. That's what happens on these, the brake and ABS lights come on, the pedal gets squishy, and it doesn't stop worth a turd. Most of us just remove the unit above the rear axle and unplug the controller behind the glove box.

 

[crobertson1]

Pete,



That would be great if that's what it is. Could you give some more details as to what to disconnect and so forth. If I take the thing off the rear axle, does anything need to be plugged or replaced?



Then I'll just search for a ground problem on the EGT gauge.



Thanks,

Craig

 

[cerberusiam]

Yeah, bad grounds and failing ABS can cause multiple problems. It could be a ground causing the ABS to fail and mess up the brakes, or, it could just be a coincidence they happened together. Grounds first, check for lines leaking, bleed them out, and then see if ya gotta dig further.



That would be my steps but I am more OCD than Pete. :-laf

 

[crobertson1]

Do you think it could be the ground for the EGT? And BTW, I'm plenty OCD! I'm just not very good mechanically!



Thanks a lot!

 

[PToombs]

:-laf OCD? Not me! Wait a minute, my paper is crooked! Ok, that's better. :-laf

Now, brakes, I removed my valve when I replaced the rear brake line. I just ran the new line straight to the hose connection for the axle. The fittings are the same. If your lines are good, and you just want to bypass the valve, there are 2 adapter fittings you need.

Here is daniels post with the numbers,

https://www.turbodieselregister.com...rum-1989-1993/170120-i-have-part-numbers.html

 

[crobertson1]

Hey thanks guys! A friend replaced the master cylinder for me and it fixed both problems! Thanks for all your help.



Craig

 

[PToombs]

Wow, that's weird! Glad that did it for ya though.

 

[crobertson1]

The only thing I can figure is that when the gauges were installed, maybe he tapped into a wire (for illumination power?) that has something to do with the brake warning lights that affected the EGT gauge. ??? So when the "ABS and brake lights on the dash come on, it affects the gauge. When the parking brake is applied, it doesn't though. Who knows? It's all good now though.

 

[JLight]

Croberson when my abs comes on and pedal are soft i need to adjust rear brakes. Also im going to take the abs out and unplug the controller like pete did

 

[JLight]

Im gonna do this IF it ever stops snowing! Weather guy says 1-2 ft maybe tues or weds

 

[crobertson1]

It's funny that this came up today. We had to have the master cylinder replaced again, due to a crappy, not long lasting, model that was installed a month ago. We were told that we need to at least adjust the rear brakes too.