2001 blazer 4.3 auto 4wd --------- abs light came on and off for couple of miles. I parked overnight now abs light stays on , while driving brake light on dash comes on and off intermitently, when brake light comes on transmission downshifts to 1st gear when brake light goes off it shifts up where it should be, abs light stays on all the time. any help would be greatly appreciated thankyou

 

I have the same problem with the (ABS) and Brake warning lights coming on intermittently,but the transmission does not shift when this happens. The advice I got here is that it is probably a bad wheel bearing leaking grease onto the (ABS) sensor.

 

speedo stopped working. tried plugging in new wheel hub on each side ,abs light still on. going to check tranny wires to speed sensor maybe its a connection problem its worth a shot

 

I have just had this problem start. Tranny not shifting properly and the ABS light comes on.
I see this is an old thread but figured WTF. post on it anyway. I was thinking the speed sensor also. Goin out to look into it in a few minutes
.

 

Speed sensor is the first thing I'd look at.

 

My AC was also messing up. it would cut in and out. The plug on top of the compressor was loose. I bent the prongs on the compressor toward the radiator. Plug was now tight. I figured the two problems were not connected.
Drove 150 miles no problems. No ABS light and transmission is shifting fine Might be because when the compressor turns on it kicks up the idle?

 

Sounds more like a bad ground issue, the PCM controlling the trans shifting shouldn't care much about the ABS system malfunctioning. Was the speedo dropping out when the trans downshifted? That and the PCM shifting commands depend on the VSS in the transfer case. If it wasn't dropping out, the speed signal was still good during the problem.


AC only kicks up the idle at idle, not when you are driving down the road!


Bad grounds can cause all sorts of weird computer issues as the power from a heavy draw item can try to find a path to ground through the grounds on the computers.

First thing I would do is hit AutoZone and get your codes read, if any. That might give a clue to the source of the issue.

 

Hi about 400 miles since fixing the plug on the ac. Still working fine.

The speedo was reading wrong or not at all when i had the shifting problem. I have a code reader. Po141 sensor 1 bank 1 is the only code. Im not looking forward to changing it. I dont think its going to come out in one piece

For now the blazer is running great
thanks