1990 renix XJ with an updated dual diaphragm brake booster, MC and prop valve from 95-95 Xj.
So everything seems to work out great with the new brakes. No leaks, solid brake power from driveway testing!
One thing is really bugging me though and will potentially spoil my day when it comes to inspections to get it out on the road again.
The warning brake light comes on and goes away during self testing as it should, and the parking brake works fine.
The only thing is that the brake warning light continues to get a little bit of power feeding somehow all the time, which makes a very constant dim warning light. Same bulb as when it gets "100%" light on.
Clues:
-Nothing else on the connector B warning dash lights is doing this (seatbelt for instance)
-I have connected the brake pressure switch from the old bendix system on to the new prop valve via the Bendix plastic plug, which all fits. If I remove the switch, the dim light is still there sp that doesnt seem to be the problem. I guess if it didnt work it would be full on warning light all the time? Or should the warning light go on when I remove the pressure switch?
-When i remove the ABS control unit under the backseat no brake warning lights work, park brake etc (since the signal goes through it)
Anyone of you guys with this swap experience that has had similiar issues? I´ve red up ALOT about this swap but not much about the brake warning light actually.
These are some diagrams for reference. Bendix ABS logic- everything through the Bendix brain Regular brakes with brake warning switch (meaning pressure diff switch I guess) Desired behaviour brake warning switch, left rear engine compartment?
If the new brake system is functioning well and reliably... and the main issue is the light being on at inspection time.... Someone very irresponsible following bad advice might unplug the bulb prior to an inspection... I can't imagine anyone actually doing this. Horrible idea.
If the new brake system is functioning well and reliably... and the main issue is the light being on at inspection time.... Someone very irresponsible following bad advice might unplug the bulb prior to an inspection... I can't imagine anyone actually doing this. Horrible idea.
that could most definitely happen with the” check anti-lock” warning bulb (not by me though of course)
The problem is that the brake warning needs to function on the self- check at key on- that together with the seat belt light turns off again automatically.
I’ll check the hand brake switch and see if that makes a difference, otherwise it’s probably the abs brain feeding a little bit of power somewhere cause I pulled a lot of stuff out. Guess it could be any of those wires causing some floating electricity…
Ok! For everyone following this thread 😁 I am happy to announce that I found the problem. For anyone else that is about to do the abs Bendix swap this is what I experienced;
after putting the new stuff in I installed the same brake light switch into the new 1995 prop valve (I want to know if my brakes wont work)
I wanted to remove the Bendix ecu under backseat but soon realized that the brake warning lights won’t work, as will not the parking brake light either since it’s all running through that little box. So that could stay.
I had pulled the two abs relays in the fuse box, since I figured I already threw all the junk out of the engine bay anyways, and also pulled the ”check anti-lock” bulb since I wouldn’t have anti lock.
But after installing everything I had a liiiiittle glow in the brake warning light always on. Not ok. Could not figure it out. But then I put the two relays back and everything works perfect! I think the ecu needs to have the circuits loaded somehow to not throw a false signal to tje red brake warning light.
just wanted to share my recent learning just out of dopamine rush from fixing this
