94 z71 Brake light/acceleration issues

Post Reply New Topic
saver40
Posts: 5
Joined: Mon Sep 15, 2014 8:31 pm

94 z71 Brake light/acceleration issues

Unread post by saver40 » Mon Sep 15, 2014 8:49 pm

Guys I need some help.
I bought a 1994 z71 350 automatic. When the truck sits for a while the parking brake light comes on within the first minute or two of driving. Soon after the light comes on I start having a slight loss in acceration at low rpm. When it gets close to shifting, at higher rpm, I have a complete loss of acceration, almost like it shifts into neutral because it revs up. If I let off the gas it shifts and then the cycle repeats. Then my speedometer starts jumping around. Sometimes my service engine light comes on with it but sometimes it doesn't. The only other problem I have is that the brakes are pretty spongy and the temp gauge hardly budges (I am no expert so I don't know if a faulty temp sensor or such could be related). After it does this and then sits for a while it doesn't do it again. As long as I drive it at least every other day it will not do this. But more than that you can bet that light will come on. When I bought it I replaced the front pads, rotors, cv shafts, fuel filter, oil and filter, air filter, plugs, tps, and knock sensor. I also had a trans shop replace all the trans seals and gaskets plus filter. I'm out of ideas. Thanks in advance for the advice.

 

User avatar
carriedi
Posts: 2279
Joined: Wed Apr 10, 2013 12:42 pm
Location: Oregon

Re: 94 z71 Brake light/acceleration issues

Unread post by carriedi » Mon Sep 15, 2014 9:03 pm

you should drive it with a scanner on it and see what the data stream is doing. See if any codes are stored in memory. this way you can verify the coolant temperature too. You can then scan the data stream for the trans too. see if the trans has codes and is slipping.
Browse "SIMILAR TOPICS" At The Bottom Of This Page.

saver40
Posts: 5
Joined: Mon Sep 15, 2014 8:31 pm

Re: 94 z71 Brake light/acceleration issues

Unread post by saver40 » Tue Sep 16, 2014 11:41 am

I took the truck to O'Reilly's and their code reader said something along the lines of unable to communicate. When I had the tranny seals and gaskets replaced at the dealership was when this problem started and I took it back to them. They ran their code reader and they cleaned some parking brake connections and said the reader was showing a bad O2 sensor. Neither of which helped.

User avatar
carriedi
Posts: 2279
Joined: Wed Apr 10, 2013 12:42 pm
Location: Oregon

Re: 94 z71 Brake light/acceleration issues

Unread post by carriedi » Tue Sep 16, 2014 9:04 pm

so is the brake light not coming on anymore?
Browse "SIMILAR TOPICS" At The Bottom Of This Page.

saver40
Posts: 5
Joined: Mon Sep 15, 2014 8:31 pm

Re: 94 z71 Brake light/acceleration issues

Unread post by saver40 » Tue Sep 16, 2014 9:07 pm

Yes it is. If I drive it often it won't happen. The longer it sits the greater the chance the light comes on and when the light comes on the other problems follow.

User avatar
carriedi
Posts: 2279
Joined: Wed Apr 10, 2013 12:42 pm
Location: Oregon

Re: 94 z71 Brake light/acceleration issues

Unread post by carriedi » Tue Sep 16, 2014 9:27 pm

how is your battery and charging system? are the battery terminals and ground connections good and clean? could there be a voltage problem?


do your truck have anti-lock brakes
Browse "SIMILAR TOPICS" At The Bottom Of This Page.

saver40
Posts: 5
Joined: Mon Sep 15, 2014 8:31 pm

Re: 94 z71 Brake light/acceleration issues

Unread post by saver40 » Tue Sep 16, 2014 9:52 pm

I can check and clean the terminals tomorrow. I know the battery is about 3 years old. Yes it has ABS.

saver40
Posts: 5
Joined: Mon Sep 15, 2014 8:31 pm

Re: 94 z71 Brake light/acceleration issues

Unread post by saver40 » Fri Oct 17, 2014 4:17 pm

Well no luck diagnosing the problem so far. Here are the clues. Parking brake light comes on when these problems occur. Truck surges, reflects this on the tach at all RPM, and/or completely loses power at high RPM. Codes have been pulled and read running lean. Temp gauge reads too low (hardly budges after running for a while). Lastly I can't trace the source but I can smell gasoline every once in a while outside of the vehicle. No visible leaks on concrete. Thanks for the help!

User avatar
carriedi
Posts: 2279
Joined: Wed Apr 10, 2013 12:42 pm
Location: Oregon

Re: 94 z71 Brake light/acceleration issues

Unread post by carriedi » Fri Oct 17, 2014 10:06 pm

because the brake light and the engine are on separate systems I would think you may have a ground problem. you should have your car driven with the scanner on to see what happens to the data stream when it starts to act up. If you loose communication when it acts up you may have a bad computer or may have a poor power or ground connection.
Browse "SIMILAR TOPICS" At The Bottom Of This Page.

Post Reply New Topic
  • Similar Topics
    Replies
    Views
    Last post