• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Startup then Limp Mode now dash lamps dim at first

F

fonecop1

New Member
Messages
188
Reaction score
0
I got ready to leave work tonight and when I pulled out the truck never shifted. I had to pull over and shut it off and restart it then it shifted through the gears. About 15 miles down the highway it lost power and the lights on the dash came on like it died but then it took off running and made it all of the way home. The SES wasn't on but I checked the codes and had:

code 81 2-3 Shift Solenoid Circuit Fault
code 84 Accelerator Pedal Position (APP) Circuit Fault
code 99 Accel Pedal Position (APP) 2.5 Volt Reference Fault

I noticed when I cycled the key to read the codes that the dash lights were really dim (about the same as not being on at all) then they came on bright and I could hear the glow plug relay kick in and then the realy would kick out and they would go really dim again. I just put 2 new ACDelco batteries in it a couple of weeks ago and just as a test I hit the starter when the lights were really dim and it turned over like normal. I think you guys are gonna tell me to go through the grounds for sure but is there anything else I need to be thinking about? Also is there one particular ground that would cause something like this?
Thanks,
Bob
 
Last edited:
Yes, grounds. Might as well do all of them, then you know they're done
 
fonecop1 said:
I got ready to leave work tonight and when I pulled out the truck never shifted. I had to pull over and shut it off and restart it then it shifted through the gears. About 15 miles down the highway it lost power and the lights on the dash came on like it died but then it took off running and made it all of the way home. The SES wasn't on but I checked the codes and had:

code 81 2-3 Shift Solenoid Circuit Fault
code 84 Accelerator Pedal Position (APP) Circuit Fault
code 99 Accel Pedal Position (APP) 2.5 Volt Reference Fault

I noticed when I cycled the key to read the codes that the dash lights were really dim (about the same as not being on at all) then they came on bright and I could hear the glow plug relay kick in and then the realy would kick out and they would go really dim again. I just put 2 new ACDelco batteries in it a couple of weeks ago and just as a test I hit the starter when the lights were really dim and it turned over like normal. I think you guys are gonna tell me to go through the grounds for sure but is there anything else I need to be thinking about? Also is there one particular ground that would cause something like this?
Thanks,
Bob
Click to expand...

Yes grounds, but also unplug the Accelerator pedal connection and plug back in a few times to make a better connection. I had mine go into limp mode when the shift solenoid (1-2, 2-3) went south, First noticed when really cold. Ended up doing all solenoids, harness, pressure manifold, and filter inside tranny and adding Lubeguard after flushing the fluid. Good ever since, and it gets fricking cold here.
 
I started on the grounds. First I did the one on the top of the rear passenger head. That one had a new connector crimped on it I guess by the dealer because I hadn't done it. There were 2 wires in itone about 10 ga and one about 16 ga, the 16 ga wire wasn't in the crimp but just wrapped around the other so I thought I had found the problem. Well that wasn't it.

Next I did the one at the very rear of the passenger side head with 2 braided wires on it. Still no change.

Next I did the 2 battery connections at the intake and all 4 connections at the batteries. I had just done the battery connection mod when I replaced the batteries but retorqued them anyway. I tried it after that and the dash lights came on normal for 2 cycles of the key and glows, on the 3rd try same thing.

I guess I am going to continue going through the grounds but I'm wondering if that will be it since I read that the one on the top rear passenger head was supposed to be the PCM.

I was wondering if it could be the ignition switch?
 
You may have more than one problem and fixing the grounds may have fix something other than the dash light problem. It certainly isn't going to hurt anything.
 
No. It is only the dash lights when you first turn on the key. While fooling with it tonight there were times when the lights aren't even dim but take a few seconds to come on. I am beginning to think it is the ignition switch.
 
It is 15 years old, I bought it new and have put every mile on it. Another reason I am leaning that way is my buddy who is a transmission mechanic said that he changed out an ignition switch to fix a wouldn't shift problem. When this began lastnight mine wouldn't shift and I just figured it was in limp mode, maybe not. After all there is the 81 code for the 2-3 shift solenoid. I had a scanner on it tonight and the solenoid looked fine driving it around. Since the solenoids are only about $16 and my trans needs serviced anyway my buddy is gonna get both solenoids and replace them when he services it.
 
Well I pulled the fender well today and went through those grounds and still no liuch. It is actually getting worse, sometimes it takes more than 5 seconds before the dash powers up. Also I noticed it sounds like there is a relay under the dash near the steering column that you can hear click right before you can hear the glow plug relay click. During testing there are sometimes that you turn the key on and 20 seconds later the dash is still dark. I still think it way be the ignition switch.
 
Starting to sound more like ignition. On the bright side your ground are clean and no money was spent:D
 
You must log in or register to reply here.
Back
Top