Motor Racing Away In Abs Module..

[rancherman]

Ok,  yesterday  I had  a couple of   issues,    didn't want to  keep running during  cold start.     After  getting the engine  warmed up and  batteries totally charged,  and  warming up the suction screen  ahead of  the  FASS drp,   it  fired right up and  ran fine...    I then  proceeded to  drive it  back to my house  from  our  shop.   1  mile.

 

Got home   and  noticed  a  weird   buzzing  noise  coming  from under the hood,  and  immediately  shut it  down and  popped the hood...     the  electric motor  on the  abs  system  was  racing away.  Even  with the   key off.

 

It  was  starting to get warm,  so I just  unhooked the  plug going into the  motor.       

 

I've had    the  brake/abs  warning light on  for  over 2 years now,  I figured  an  axle  sensor  is  kaput.    Was going to  remedy that    when   I got the   axle  apart  for  new ball joints  this spring.  

 

any  thoughts  on   what  may be going on?       The motor  acted like it wasn't  under any load at all,   I was  wondering if  something  broke./  came  unhooked  from  whatever   that motor  drives...  ie    the  valve  that actuates  the  pulses  to the   brakes??       Then the  computer  sensed  it  didn't complete  a test  cycle and  continued to    run the  motor??

[Mopar1973Man]

ABS module burned up. Rather a common issue where the electronics switching of the module burns up the controller of the pump motor. Just for safety sake I would double check the alternator AC noise levels since a electronic device failed. But I look like now you need a ABS modules and a set of ABS sensors.

[rancherman]

so, for now,   running the motor unhooked  won't affect   other  electronics?       (throw codes  in  pcm  )     

 

ahem,   I  guess  I've never been  a total  advocate  of   abs..      this may  not get fixed  'right away'.

[Mopar1973Man]

As long as the speedometer is still functional you'll be fine.

 

No. The only code thrown will be internal to the ABS module keeping the light running. The only way to see the code will be with the DRBIII tool since most ABS code are not sent as P codes except the P0500 code.

[rancherman]

the  first  plug  we  unhooked yesterday  (the big one  on top of   module)  did  make the  speedo  quit.... as  well as  the    motor.   That's  when  we spotted the   motor-run  plug.    

 

I'll  check for   ac  noise,   I do remember  having  extremely  high  volts  on  dash  right after  starting  the engine  yesterday..   It was  pegged  for about 10  seconds....  but  came  back to earth,   and  been  rock solid  at  14.5  volts  since.

 

I'll snag  the module off  the   '98  to   see if   that's  all   i'll need,    I might just get the  burnt one   rebuilt.      A  quick   search   tells me  rebuilding mine  will run  about  50-60 bucks,      One  ready to install is  about 200.

Thanks!

[diesel4life]

Isnt the abs module fused? I remember on our old Tahoe I was driving down tne road one day went to hit the brakes and the pedal went to the floor, then started kicking back at me. I literally had zero brakes and rolled through a stop sign...thank god it happened at 3am on my way to work. Anyhow, I simply pulled the big fuse to disable the module and it let me have power brakes again, no abs but not a concern to me.

[rancherman]

Im sure it's fused,   I just  did it  at the motor  because it sounded like it was  turning  10,000 rpm,  and  getting  quite warm.     I'll probably  pull the fuse  and  reconnect the motor,  just to keep   crud out of the connector.

 

Speaking of  connectors,     Is  there  ANYWHERE   a  person  can  find  out how  to  disconnect  various  connectors?   I swear,   each one  is  it's  own   maze  of     locks,  snaps,   and   barbs..   

[Mopar1973Man]

If you unhook and of the top connectors the speedometer will drop dead. Speedometer signal comes from the ABS module so all the top plugs have to remain hooked. As for the motor connection you can leave that unhooked.

 

Red tabbed connectors you just slide over and then squeeze the release and pull.