New truck to me, 1990 W250, 4 speed manual. I just put a rear locker in the truck, rebuilt the brakes in all four corners and now have a spongy pedal and both the brake and anti lock lights are on. I pulled the abs sensor out of the top of the differential it was clean (no shavings on it). I also bled the system starting at the valve above the drivers side rear tire. I did not have this issue or the lights prior to the brake job.

Any suggestions on where to start?

 

Spongy pedal means air in the system. Have a friend help you bleed them again, and make sure you are getting good flow out all the bleeders. (one at a time..... )

 

I just dont understand how without touching anything electrical while doing the brakes, I can now have the brake and anti lock dash lights on. I also just noticed that I'm getting the brake lights stuck on even though the key is out of the ignition. What gives?

 

Does the locker unit have a tone ring for the abs system?

 

Yes, it does have the tone ring as the stock carrier is still in the differential. It was a Spartan lunchbox unit.

 

Couple different things can cause your issue, but, what they all basically boil down to is, the safety valve in the proportioning valve has been tripped. Can happen while bleeding, in fact, it is the valve doing its job..... Re-bleed the brakes. Get the air out, and make sure both circuits are working, should solve the problem.

 

How does the valve get reset as I don't see a "button" on it like on my K20 pickup. And, your talking about the proportioning valve up on the forward drivers side frame rail correct, not the RWAL valve on the rear frame rail?

I did just last night replace the MC and booster. I can barely get any fluid out of the RWAL now or either rear wheel. I did bench bleed the MC before install but saw very little air exit the unit.

 

Have a friend pump up the brakes, and hold pressure, then crack open one of the FRONT bleeder valves. May have to do it a couple times to re-center the valve. After that, you should be able to get pressure from the rears.

 

Update:
Did the brake job at all four corners as previously described. Lights on, no pedal, very little fluid coming out when bleeding.

Replaced MC and booster. Bench bled the MC, still no fluid anywhere when bleeding.

Called the mobile brake mech here in town who came over and rebled the MC, then each wheel and all was well! Best 100.00 I ever spent