New to group and an ABS problem with my 91TC

Derekw66 · September 10, 2018

So, any help anyone can offer. I am new to the group but have had my TC for quite some time. Recently my ABS light and brake light on and I had no power brakes. Upon inspecting the fuse box for the ABS, the 30 amp fuse was melted, as well as the fuse box. The accumulator is relatively new and does not run for more than 25 to 35 seconds so I can’t imagine it being the culprit. Does anybody have an idea as to why that wire got/gets so hot? Also, it’s worth noting my battery goes dead within two days but I can’t see the drain anywhere. I’ll add some pics of my findings. Thank you in advance.

Hemi Dude · September 11, 2018

This is not an uncommon problem. If the accumulator is in fact OK, then the pump is pulling too much current. If that is the case, put an ammeter in the power circuit and connect directly to the battery and see what the current draw is to operate the pump. We do find that this condition is usually due to a defective accumulator, though.

Turbo Kane · September 12, 2018

I have an entire ABS harness I would be willing to sell. Private message me if interested.

jderden · September 13, 2018

Hello ;

I am also having a problem with my 1989 Car, 4 cyl, auto,TC draining the battery appox. every two days. If you find out what is draining your battery , please let me know.

I have been chasing my problem for some time now, changed battery and brake accumulator with no help.

bilk · September 13, 2018

Check your trunk and spare tire compartment lights and under the hood, they may be on all the time, mine were.

Edited September 13, 2018 by bilk
added info (see edit history)

Reaper1 · September 13, 2018

To add to the last suggestion, if you use a DVM, you can monitor the amp draw from the battery. Hook that up and start pulling fuses until the draw goes down. Then, start trouble shooting that circuit.

Derekw66 · September 13, 2018

I'll do all of these recommendations and report back. Heading to Indy for the weekend but I'll check back next week with some positive results hopefully.

Thank you for the tips gtuys.

Derekw66 · September 21, 2018

Well, I did a parasitic drop test on the system and found nothing. My battery is at least 10 years old so I may just get a new one for good measure. It may just nothold a charge very well anymore.

As for the abs fuse melting, I think it may be attributed to when I bled the rear brakes during my system flush two days prior to having the melted circuit. In order to bleed the rear brakes (for those that don’t know) the abs has to be running constantly to push the fluid out. I don’t think it had ever been done.

Reaper1 · September 24, 2018

Yeah, a 10 year old battery is getting up there.

Agreed that if the ABS system is let run too long during that procedure it could cause issues. I think I remember there being a caution about how long to let it run?

johngoodman · October 15, 2018

On 9/13/2018 at 12:35 AM, jderden said:

Hello ;

I am also having a problem with my 1989 Car, 4 cyl, auto,TC draining the battery appox. every two days. If you find out what is draining your battery , please let me know.

I have been chasing my problem for some time now, changed battery and brake accumulator with no help.

I used to have the same problem - turns out it was the pull-down motor for the top. Use a 3/4" wrench on the manual override (in the trunk) to check that it's fully seated. If you hear a click, you'll know it's the problem.

John

Derekw66 · October 15, 2018

I would do a parasitic voltage drop test on your TC. I had the luxury of knowing which fuse melted, kinda easy to spot, and after seeing my battery was more than 10 years old, I,m Confident my problem is sorted. No issues since my last post.

Hemi Dude · October 19, 2018

On 9/10/2018 at 11:42 AM, Derekw66 said:

So, any help anyone can offer. I am new to the group but have had my TC for quite some time. Recently my ABS light and brake light on and I had no power brakes. Upon inspecting the fuse box for the ABS, the 30 amp fuse was melted, as well as the fuse box. The accumulator is relatively new and does not run for more than 25 to 35 seconds so I can’t imagine it being the culprit. Does anybody have an idea as to why that wire got/gets so hot? Also, it’s worth noting my battery goes dead within two days but I can’t see the drain anywhere. I’ll add some pics of my findings. Thank you in advance.

Something I found on RockAuto which you should all take a look at if you need to do electrical repairs. The DORMAN 85665 Fuse Holder - Blade Style; 12 Gauge w/o Cap looks most promising for the ABS circuit repair.