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Discussion Starter #1
My 94 uses the Kelsey-Hayes EBC4 ABS unit. The ABS light has been on since I bought the truck. I bought another ABS unit off ebay before I knew there was a difference between the Blazer unit and the pickup unit, and of course I bought a Blazer one.

I'm getting codes for the control valves and open/shorted pump motor relay. I've read everywhere that the main problem with these is that the relay sticks and burns everything up.

I took my Blazer ABS unit apart to see if I can swap out parts, and I think it boils down to what you see in the pictures. This part is different of course, so I can't just stick this in - the connector at the top that is visible in the picture is a 3-pin, while mine is a 2-pin.

Has anyone had one of these apart and successfully repaired it? I'd really like to find a newer style unit to put in, but have no idea if anything would even work. I know most people on this forum just remove the ABS altogether, but I'd like to have mine working.


 

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Discussion Starter #2
This is my second time posting about ABS in the past couple years, and once again, not a single response. I'm convinced I'm the only person in the world with a 1994 with ABS problems. Guess I'll figure it out myself.
 

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Mr Goodwrench's Evil Twin
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Have you considered sending the module out for repair? There are companies that specialize in automotive module repairs/rebuilds. Whether it be abs, powertrain, transmission, instrument cluster etc. A company called Module Master will rebuild that abs module for a little over $100 and a turnaround of a few days. They warranty the rebuild for 5 years too. That's usually the best solution for the kelsey-hayes abs modules. Just my 2 cents.
 

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Discussion Starter #5
I've looked at quite a few web sites that rebuild ABS modules. But, it's never my model that's listed - only the newer ones. I'm guessing the module (the part with the electronics) can be separated from the pump, so they're easier to deal with. I found a few sites that USED TO sell refurbished units, but they started at $750 and none of them sell them anymore (not that I would pay that much anyway).


Neither of the sites you mentioned lists my ABS module.


Thanks for responding though. :)
 

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Mr Goodwrench's Evil Twin
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If you contact them with the relevant ebcm info and description of the problem, there's a good chance they can help. Even if your particular module isn't listed on their website. Never hurts to ask if they can do it.
 

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Been there Done it
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Considered a used one? I realize you could get another bad one, but there are a lot of 94's in the yards. I scrapped a 4x4 RCSB in the spring due to rust. The ABS was working. I know right where it is in the yard if it comes down to it.
Is the Astro van unit same as truck or Blazer or a 3rd model?

Here's some info on diagnosing and bleeding them:
https://www.aa1car.com/library/abs_kelseyhayes.htm

I dug out the wiring diagrams for the Blazer and the pickup and do see that the pickup has one more wire. IIRC on the 94 pickup I had, the ABS was not functional when in 4wd. I think you could get the Blazer pump to work by just leaving out that wire and using the correct plug for the pump with a couple splices. BTW EBC4 is sensitive to a good ground.
Here are the 2 diagrams side by side:

 

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Discussion Starter #9
I think it boils down to two different models. My pickup has the one on the left. I think the Blazers have the one on the right. I tried calling the local yard a couple weeks ago. He said he was too busy to check if he had any, but would call me back. Of course he never did, and I haven't made it out there. There's about 10 of them listed on ebay, but they're all the Blazer style with the different connections. And thanks, but I already found that link long ago and read up on them.





 

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Discussion Starter #10
So, I went to the junkyard this weekend and picked up another ABS unit. Got it in, got it bled, still have the Anti-Lock light on. The code this time is DTC 86: Shorted Anti-Lock Indicator Light. This doesn't make any sense to me seeing how the indicator light is flashing the trouble codes. How can it be shorted then? Power to that light comes from the fuse panel to the dash, and then it's grounded through the ABS unit. I'm assuming that means this ABS unit is also no good. I've searched online for about three hours now and can't find anything about troubleshooting this code. The Mitchell manual shows step 1: Connect a Tech 1. That rules me out.
 

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Discussion Starter #11
I finally came across this and figured I'd give it a try. I had disconnected the battery for about 20 minutes, but that didn't work. This apparently did. My ABS light is off anyway. I haven't driven it yet to see if it comes back on.


CLEARING FAULT CODES
1) Turn ignition on. Using jumper wire, connect DLC terminal
"H" to terminal "A" for 2 seconds. See
Fig. 2
. Remove jumper wire for
one second. Again, connect DLC terminal "H" to "A" for 2 seconds.
Remove jumper wire.
2) Fault codes are cleared when ANTI-LOCK and BRAKE lights
illuminate, then turn off. Turn ignition off. Verify codes are
cleared. See
RETRIEVING CODES
. If ANTI-LOCK light is on continuously,
Tech 1 can be used to clear codes.
 

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That'll turn the lights off for a while, but won't fix the problem. If something isn't working correctly in the system they will come right back.
 

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Discussion Starter #14
I don't remember if it was him or the Module Masters, but I sent an email and they responded back that they don't deal with my unit. Doesn't matter anymore. The one from the junkyard has been in a few weeks now. I've activated the ABS once so far and it's worked great. The light on the dash is still off also, oldeerslayer.
 

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Hi Kevin, thanks for this thread. I realize that most people just disconnect their abs at the first sign of trouble. Which I have done on two of my s10 fleet, mostly because there exist almost no information on these units. So, thanks for the pics. From my research, most of the failures are either the motor relay, one of the actuator coils or the motor. All these conditions can me verified using a DVM from the outside of the case. What I haven't been able to locate is the pin-out of the coils and the motor relay at the connectors nor the resistance values. If you have this information I would greatly appreciate the information. If not I'll post what I find upon disassembly. But since you have the unit disassembled you should be able to verify the integrity of the components and possibly replace the "bad" component(s) on yours with component(s) from the one you bought on e-bay, even if it is the "other" connector interface. Thanks again, I probably wouldn't have bothered to disassemble mine if I hadn't stumbled on your post.
 

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Welcome to the Forum.
Please check the dates on the threads you are responding to. Here is a link to the rules. They describe how to provide a link to dead threads like this one.

 
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