I have a 1994 LT1 Automatic with ASB/ASR Code 61. Working through the manual as well as reading all the posts on this Forum and others relating to ABS problems, I have checked all wires and harnesses and connections related to the EBTCM Harness and BPM. During the steps outlined in the manual pertaining to the two main circuits involved in Code 61 #479 and #854, after successfully completing the first 8 Steps to diagnose #479 (Pump "ON" Input), upon reaching Step 10 which pertains to #854 (Pump Motor Relay Control) I am stumped. The manual calls for checking resistance between EBTCM Terminals #5 and #3 and states that if the reading is "OL" (INFINITE) - Repair Short to Ground on Circuit #854. Terminal #3 is one of the three Grounds on the EBTCM Harness and Terminal #5 is the EBTCM #854 (Pump Motor Relay Control) wire which runs to Terminal #14 of the BPM Harness. As far as I can tell, that is Circuit #854 and the wire is not chaffed, broken, or grounded. Electrical is not my niche, so I would think that if the #854 wire of Terminal #5 was shorted to the Terminal #3 Ground it would show continuity upon testing resistance, however I get an "OL" reading which the manual states would be a result of Circuit #854 Shorted to Ground. 1. I don't understand what the manual is trying to tell me. and 2. I don't find anything wrong with Circuit #854 which is a pink wire that only runs between EBTCM #5 and BPM #14. I do not have a Tech 1 and I don't know how to jump the motor to see if it runs. I have completed all the other steps in the manual and all pass except the Step 10 test. What am I missing?? I also have cleaned the wheel sensors and inspected and tested all wires from the ABS compartment to the front of the car for continuity. My thoughts are that the Pump Motor may be shorted, but test number 5 calls for checking resistance between the BPM Valve Connector Terminals and the Relay Connector Terminals and everything checked out and I would think if the motor was Grounded, it would have shown up in that test. HELP DESPERATELY NEEDED!!

 

OL would be open so answer is no. Off to step 11 looking for voltage.

 

What did you do in step 6 or do you have breakout box?

 

Exactly my point of not understanding what the manual is telling me. The manual states the following: Measure the resistance between Terminals 5 and 3. (Does the meter read "OL" (INFINITE) ? NO = go to Step 11 YES = Repair Short to Ground CKT 854 . My meter reads "OL" and that is why I am lost. I went through the following Steps and the result of Step 11 was .4 volts so the answer was NO the voltage is not near B+. Step 12 I have untapped, inspected, and tested all the wires from the the ABS Harness and all the wires from the ABS Compartment to the front of the car for continuity and found no chaffed, broken, or shorted wires.

 

I do have a J39700 Breakout Box with the proper ABS Module J39700-10 ABS/ASR System Adapter Cable, however I bought it used and not sure of the condition so for the tests requiring the Breakout Box, I tested with and without the Breakout Box and got the same readings using the Multimeter directly on the listed Terminals. Step 13 requires a Tech1 so as to check if the motor runs so I can't go forward. I need to find out how to get power to the motor to see if it runs and I don't want to short something out doing so. I saw a thread on an older model stating witch wires to connect to power the motor, however the older unit had different color wires and I don't want to guess wrong. I failed to mention that I have replaced the ASR and Adjusted the Replacement and replaced the EBTCM (both with used units) and get the same results. I really feel the motor has failed but can't prove that theory at this point with my lack of electrical knowledge. Things I thought make sense don't necessarily make sense electrically, I guess you could say. I actually thought that when I performed the Test #5 whereas you check resistance between the BPM VALVE CONNECTOR Terminals and the RELAY CONNECTOR Terminals that either HIGH RESISTANCE or OPEN CURCUIT would indicate a bad motor but all the readings were good. However, I don't even know if I was thinking correctly. I have purchased replacement ABS Pump and Harness, however if there is a Short, I would like to find it before going through the hassle of replacing (and attempting to bleed a new unit) only to short it out. Already risked an EBTCM.

 

Have you replaced the pump relay? Why did you replace ebtcm?

 

I originally had 3 codes, 61 - Pump Motor / Relay Error, 66 - Adjuster Assembly Error, and 72 - Serial Data Link Error. I checked the Relays and they were Good however I purchased new ones and they tested within the same range (kept them as spares). Replaced and Adjusted the ASR Assembly and cured the Code 66. Replaced the EBTCM cured the Code 72, now still have the Code 61. Relays were tested using FSM instructions for Code 61. I was hoping to find the problem and fix it without changing the pump because I really am stressing over not being able to bleed the air out of the pump. Some say you don't need a Tech 1 but other say you do. I actually purchased the Pump in hopes that if it was the motor, I could figure a way to change it out without having to break the lines, i.e. holding the unit in place and removing the bottom plate and working from the bottom, however I don't know if it can be done or if removing the motor would subject the pump to air. At the stage to just replace the Pump Assembly when it gets here tomorrow and hope for the best bleeding it and hope it cures the problem since I have been dealing with it since January a little bit at a time. I have refreshed almost everything on the car in the last 7 years then this started one day when I was going to go get an inspection. Never had an ABS/ASR problem before that day and I just want to drive and enjoy it. I have been able to find and repair everything else it has thrown at me, but this is whipping me and I don't want to give up.

 

I really love the performance of the Computerized, Electronic Fuel Injection ERA, but I sure miss the old Spark, Fuel, Air, and GO ERA!!

 

So, I figured out how to jump the motor, after finding the positive lead to the motor, as it plugs into the same circuit board as the relays. After jumping the motor, it does not run, so I feel as though that is a problem if not the problem. I really wish I could just change out the motor, but I don't know if that is possible, so I will change out the Pump and report the outcome, in case anyone is interested.

 

Well, no luck as yet removing the lines from the pump. Trying not to break any, which after research seems highly unlikely. Tried different Line Wrenches, all seem to want to flex open and I don't want to strip the nut. I have been soaking the fittings with PB BLASTER, without positive results. Not wanting to be negative, but looking like possibly going to end up replacing brake lines. Last ditch effort, I am going to cut a slit into a socket and place it on the fitting and use vice grips so as to keep it from flexing open and see what happens. Knowing that if any of the lines break, the car is out on commission until new lines are installed, is a tough choice. I can only imagine how much fun running brake lines will be and not really wanting to find out. I would have never dreamed removing the lines from the pump would be the biggest problem. Had the bright idea of using heat and not wanting to put flame inside the car, I used a heat gun and got the fitting quite hot before thinking it was not such a good idea with fluid in the lines. Figured freeing up the lines would keep them from turning with the flare nut so started soaking them, but after 3 days of spraying and soaking nothing has budged. In the 7 years I have had the car, I haven't heard of anyone having to replace the ABS Pump so I guess I am just lucky that way. Should go buy a lotto ticket!! Wish me luck!!

 

My asr light comes on under hard acceleration. Going to check codes jumping "A" to "C" on ALDL tomorrow. The motor being talked about is located where? Is it in the doghouse behind drivers seat? 1993 Ruby, six speed.

 

It is in drivers side compartment. Plate bolts in. Lowering it may give better access to brake lines.

 

Finally removed the pump without breaking any lines, thanks to many days soaking with PB Blaster and the purchase of some crows foot line wrenches. The pump motor was seized, so for sure the code 61 was correct. If the relays are not the problem then its either the wiring or the motor. I still do not understand why the testing did not show the motor shorted, however I learned how to test the motor. Replacement pump installed, so it's all good until the next repair adventure. THANKS TO ALL for the interest and input and I hope my adventure helps someone in the future.

 

Good job

 

Where did you get the pump? Was it used or rebuilt? Part number?

 

I bought a used pump from Mirrock Corvette who is a recycler of Corvette parts. The pump for 92 through 94 is the same, some advertise the 95 and 96 in that group, but they are wrong, the 95 and 96 have a different pump and different rear wheel sensors.

 

I saw one listed on Ebay and it was listed for a 93 but to make sure if it is the correct part. Thought maybe they had a change midway through the year. They may have been referring to the brake control module which came with it. Thinking of getting it and change module out first as unable to pull any codes, just ERR. No connectivity between ecm and the brake control module.
Getting to old to climb under the car and to stubborn to have someone else do it that knows little about the car.

 

Can all the connectors be disconnected without taking the bottom plate off. I am only
replacing the ebtcm, and the one coming has the complete harness along with the pump but wanted to use that harness. Also it looks like a single screw holds that harness connection on the top of ebtcm, is that all that holds it? Lot of tape on the other end where it looks like a screw could go also.