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89 K1500 Brake Code - Help

cameronc

By cameronc
in Ask A GM Technician

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cameronc Enthusiast

cameronc

Posted
Posted

I have a 89 K1500 pickup. On my way home from a fishig trip the other day my brake light came on. After i drove a few miles the light starting flashing. I unhooked the battery and it went out for a few days. On my way home from work yesterday it came on again doing the same thing. It flashes 9 times, then steady, then 9times, and repeats itself. I dont know if its a code 9 or 99. But i wasnt even aware that these older trucks even had brake codes. Can someone please help me with this crazy flashing brake light on my dash. HA HA. I have checked the fluid and plug-ins, doesnt seem to be anything wrong and the brake still work perfect. Thanks for your help.

bill190 Enthusiast

bill190

Posted
Posted

Do you have anti-lock brakes?

 

And specifically do you have rear wheel only anti-lock brakes?

 

If yes, code 9 would be a problem with the speed signal to the anti-lock brakes (according to my 1992 factory service manual). Yours *could* be some other problem!

 

To find this problem the quickest, you would need a multimeter, know how to use a multimeter, and need a factory service manual for your year and model vehicle (get from dealer).

 

The factory service manual includes a wiring diagram of the anti-lock brake system, lists various anti-lock brake codes and what they mean, and gives detailed troubleshooting instructions for finding the exact problem.

 

Just like you need the right tools for automotive work, the factory service manual is another tool to help you diagnose the problem and give you instructions on fixing the problem.

cameronc Enthusiast

cameronc

Posted
  • Author
Posted

I got the code read and it said it was an open circuit to speed sensor. Sometimes my speedometer quits working when i am driving down the road which would make sense, but if i tap the dash the speedometer starts working again whichs makes me think its in the guage cluster and not the sensor. So if that is the problem would that make the code go off? Also does anyone know if a 92-94 cluster will work in my truck. If I do have to replace the cluster I like the 92-94 cluster better with the needle guages instead of mine. Looking at them they look the same in the truck but will it plug in and everythig work. Please help. THANKS

allchevy New Member

allchevy

Posted
Posted
I got the code read and it said it was an open circuit to speed sensor. Sometimes my speedometer quits working when i am driving down the road which would make sense, but if i tap the dash the speedometer starts working again whichs makes me think its in the guage cluster and not the sensor. So if that is the problem would that make the code go off? Also does anyone know if a 92-94 cluster will work in my truck. If I do have to replace the cluster I like the 92-94 cluster better with the needle guages instead of mine. Looking at them they look the same in the truck but will it plug in and everythig work. Please help. THANKS

 

Exact same problem with my 89. Pulled the vss connector and it was full of trans fluid. Leaking past the seal I suspect. Replaced. Erased codes and all was well for about 20 miles. Then speedo stopped working again and flashing brake light (code 9) came back on. Tapped speedo and it came back on as usual. Guess the next step will be to pull the cluster and see if I can find a short or loose connection. I had figured the cluster was the best bet but since the vss was leaking anyway and it was only $25 no big deal to replace.

 

Jim

Wingnut Senior Enthusiast

Wingnut

Posted
Posted

I wish this forum was around when I had my '89. It did EXACTLY the same thing with the 9 flashes. Everything worked perfectly though. ABS (rear only) worked great, stopped great, etc. I got so frustrated that eventually I just stuck a piece of black electrical tape over the flashing light and called it good.

allchevy New Member

allchevy

Posted
Posted
Did the cluster fix your truck?

 

If that question was for me: I haven't checked it out yet. I would think that since a tap gets the speedo working again something is loose or shorting. I'm sure the trick will be in locating it. But I'll give it a shot.

cameronc Enthusiast

cameronc

Posted
  • Author
Posted

Do you guys know if a 92-94 cluster will work in my truck? That is an upgrade i would like to make if i change clusters. I think the only year without a tach is 94 though. They look the same but I was wondering if it woud plug in and work or not?

  • 3 weeks later...
allchevy New Member

allchevy

Posted
Posted
Did the cluster fix your truck?

 

If that question was for me: I haven't checked it out yet. I would think that since a tap gets the speedo working again something is loose or shorting. I'm sure the trick will be in locating it. But I'll give it a shot.

 

 

Just an update. Pulled the speedo cluster, cleaned the contacts and reinstalled. No fix. Now battery cluster doesn't work :D . Couldn't figure out how to pull whole instrument cluster out and was afraid to pull on it too hard. So couldn't check to see if there was a crack or anything on it.

 

I noticed the speedo is driven by some sort of motor or magnetic winding. Still thinking problem is in that particular cluster since a tap on the front gets it working again. I'll continue to troubleshoot it but I need to get it through inspection soon. So far I've found that if I make sure the speedo is always working (tapping on it) I don't get any codes.

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