Hello I have a 99 4x4 blazer ls 2dr and when I bought it it would blow the 20amp ecm fuse and cut the motor out every time I used the high beams, wouldn't start till I cut off the high beams and put new fuse in. So I took it all apart to find a really cheap looking remote start system. It was intertwined with almost everything, so I found the after market wiring harness and cut all the wires going into the stock wires, taped it up. Everything was great the problem was completely gone, then at one point I went to use the high beams and it cut the motor out...so it came back..
for one, then later that night my brake pedal locks up and I hear whirring sound coming from what seems to be the abs module. To further explain the brake lock up, the pedal locked in place as in would not go down with all my force on it and the brakes would not work. When It happened there was a pile of snow and ice I hit that thankfully saved me. PLEASE HELP ME THIS IS THE WORST PROBLEM I HAVE EVERY HAD IN ANY VEHICLE.

 

When you say you reconnected the original wires for the wiring harness, how did you re-make the connections? You might have a bad or loose connection among those you tried to fix. High-quality crimping or well-performed soldering might be necessary to do it properly. (If you know what a cold solder joint is, you probably know how to do good soldering.)


The whirring sound is likely the ABS module starting. The ABS might have been working properly considering the conditions you described. With ABS you can still lose control or it will make your stopping distance longer while giving some control.

 

they weren't cut, instead they stripped the insulation and ran there wire through the factory. So maybe it go damaged along the way ? It didn't appear too have any damage. The abs light keeps going off then coming back on after a minute of driving and what do you mean it was working properly? I literally had zero brakes.

 

Regarding the wiring, that is good that the factory harness wires were not cut. Could it be possible that the electrical tape you used could have come loose exposing something that could be shorting to ground? With electrical issues in which the symptoms seem to show up without warning I always think of something in the wires that could be damaged; e.g. a break or short. That everything seemed to work after your repair and then suddenly go bad made me think of that. If that is the case, I can highly recommend the self-fusing silicone tape often found under the brand name Rescue-Tape. It does more than just stick, it actually fuses to itself.

As for your ABS system, you had no brakes at all? Yes that would be a problem! That there was snow around I had assumed that perhaps you had hit some ice. Even with ABS, a car will slide on ice. Perhaps you have an independent problem with the brakes? The ABS modules can be hard to bleed properly.

Good Luck

 

I will replace all the tape with that stuff and keep looking I guess, this really has me stumped...checked all other fuses and relay, they check out. For the abs, definitely not if I hit a patch of ice it would still pump the break in order to lock them in the first place...in this senario the pedal wouldn't move whatsoever. Thank you for your help this is a difficult one.

 

YIKES!!!!! The brake pedal wouldn't move at all??? NOT GOOD... I pray you figure it out before something bad happens... Your issue is beyond any help I can offer but do keep us posted and good luck...

 

Yea this is something els...so I took the wiring harnesses out for the multifunction switch and the ignition switch and properly soldered the joints where they cut into it and taped it up with 3m electrical tape...now it won't start, hazards and turn signals don't work, high beams still kill the motor. More things that may be important info...the drl stay on I've tried everything to turn them off but nothing works, the dash light dimmer switch used to have a little click at the bottom to turn of the dash illumination off. It still works but the click went away, when I lock the doors it keeps the drivers side door unlocked even though my keys aren't in the ignition. Please someone help if they can, I am absolutely stumped.

not only that but I'm working on this in -12 with 20 mph winds.

 

Just to cover all the bases; Is the charging system working correctly and is the battery is fully charged? Also Are you familiar with the proper functioning of the DRL? When you first start the truck, the lights should stay off but as soon as you put it into gear the DRL or the headlights (with the side lights) will come on depending on the amount of ambient light.

Are you able to get the lights to work correctly if you take out the high-beam fuse? I'm wondering if there are any other fuses you can take out that would result in the rest of the system then working correctly. This could give a clue to what part of the circuit is faulty.

But with this constellation of symptoms, I'm thinking that there could be some problem with the body control module (BCM). This is a simple computer/logic system that takes in the state of switches and other inputs (e.g. ambient light sensor) and then applies power to the proper relays that power things such as the headlights, door locks, retained accessory power, etc. In the GM service manual I have, it says that it can be damaged by electric shocks. Hopefully for you the BCM is instead getting faulty inputs because of the wiring rather than damaged itself.

With the proper scan tool, the BCM can be checked for error codes. Note that these codes do not trigger the "check engine light". One of your local parts stores might have a scan tool that could read these that they could use on your truck. When I wanted to get the codes for the ABS error I got, the first parts store I went to did not have a code reader that was sophisticated enough but fortunately the second one did.

In my copy of the 1999 GM Service Manual, the part number for the scan tool used for checking the BCM is 7000081.

 

Would a pro grade repair
​​​​​​manual have the information I need?

 

It would definitively have the factory wiring diagrams if you buy the whole set. Normally two or three books depending on the year and model.

I for one would go and look deeper into that aftermarket addition. Try to find the wiring diagram of the aftermarket thingy and the installation instruction. It may have come with some bridging behind the fuses. At some point there is a connection between circuits that should not be connected and IMHO I would suspect a leftover or even some redneck repair.