1986 Chev Corvette - ABS Light

[ricmorin]

Hello everyone,

We got this beast here with an ABS light. Comes on after a little driving. It's a Bosch C4 system and there is no way to communicate with it without a KentMoore J35890. Needless to say I don't own one. Anyone have any experience with these? Any suggestions? I was going to just scope the speed sensors but I don't want to spend much time if I'm not going to fix this thing.

[brianp87]

sorry.

[steven kiser]

i feel for you on this one. i wouldn't even start to look at this unless i got a commitment from the customer. i see these on occasion where a person brings something in that no one else will work on and all my rules of diagnostic charges go out the window. if they want to diagnose it, i will, and charge accordingly. however i will not roll the charge into the job like i will on many other instances. i would have disclaimers that make the ones at hospitals look like a one sentence blurb. just a quickie here, look and see if any hydraulic parts have been replaced and see if the pressure switch lead at the prop valve is disconnected and or grounded. if there is any air in the system it will trigger the abs light. if i recall when pressure bleeding and we all know pressure is the only way to get the air out, you have to manually (if you don't have the oem tool) activate the pump and module to flush out all the air. now i'm going from memory here but i think the only issue that will cause the light to come on at start up is an electrical failure at the module such as relay missing, main abs (motor) fuse blown or i've seen the main plug at the module disconnected because of easily activated abs. in my area with sand on the roads 24, 265 older g.m abs systems activate so easily that owners want the shut down. my daughter had an older blazer and there was always sand near the stop sign at the bottom of a long hill near her house and if she stepped on the brakes in the sand the abs would trigger and she would coast through into the intersection. basically i'm giving the long version of "make sure the customer knows" what they're getting into. maybe it was disconnected for a reason. all the early versions of abs were more dangerous when the were working than when disabled. at least when driven in areas where there was sand on the road.

[marcdaniels]

Its been a while since we had one of that vintage here but if my memory serves me won't the mastertech communicate with it with the correct adapter? I know our mastertech has a special adapter for the vettes and F-bodies due to higher speed communications. Just a thought if you have one or could get your hands on one.

[ricmorin]

Its been a while since we had one of that vintage here but if my memory serves me won't the mastertech communicate with it with the correct adapter? I know our mastertech has a special adapter for the vettes and F-bodies due to higher speed communications. Just a thought if you have one or could get your hands on one.

I wish that were so. I have both a Mastertech and a Tech2. No go. The ONLY communication is with the J tool. And you have to plug the J tool directly inline with the main controller connector from what I can see. I sent the car down the road.

[brianp87]

I woulda done the same. unless i was sitting on my hands.

[wbuxton]

A good run is better than a bad stand.

[ricmorin]

I'm way too busy right now. I'd gladly do it if I were equipped or there was a decent workaround. I'm booking middle of next week as it is. It's going to be in the high 90's this week and AC work is crazy. Feast or Famine.

[wbuxton]

High 90's??? Our snow plows rust up down here when it gets that hot, I think. Ain't seen a snow plow since I went to Colorado.