LB7: Shift indicator issues

[dcpjfs432]

When my 04 GMC Sierra lb7 gets cold the shift indicator on the dash doesn’t work or works on and off and when it goes off the trans temperature gauge doesn’t work. Any idea on what would cause that I changed the sensor under the dash with no fix??


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[TheBac]

Sounds like one of two things to me. Either NSBU switch hates the cold or the cluster itself has some issues. Im leaning toward cluster solder joints are brittle.

 

[dcpjfs432]

Okay is there anyway to test the cluster to tell?



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[TheBac]

Not really. When the solder starts to fail they start to have issues like you detail.

 

[SoCalMike]

Not really. When the solder starts to fail they start to have issues like you detail.

Could you open the cluster and resolder the contacts?

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[TheBac]

Yes you could.

 

[dcpjfs432]

Okay thanks guys
I’ll see what I can do


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[THEFERMANATOR]

When my 04 GMC Sierra lb7 gets cold the shift indicator on the dash doesn’t work or works on and off and when it goes off the trans temperature gauge doesn’t work. Any idea on what would cause that I changed the sensor under the dash with no fix??


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Is this your only 2 problems? The gear indicator is a known cluster issue, but trans temp going out at the same time while everything else is working sounds more like a data bus issue with the tcm to me. It sounds odd that you lose both trans feeds at the same time while the rest stays on, which leads me to think your TCM stops transmitting j1850 when its cold. Another thing to check when it does it is try tow haul mode. The cluster light will probably come on, but check to see if the trans actually changes the shift/lockup to tow/haul or not. If it doesn't, then you know the TCM isn't seeing or transmitting j1850.

 

[dcpjfs432]

Is this your only 2 problems? The gear indicator is a known cluster issue, but trans temp going out at the same time while everything else is working sounds more like a data bus issue with the tcm to me. It sounds odd that you lose both trans feeds at the same time while the rest stays on, which leads me to think your TCM stops transmitting j1850 when its cold. Another thing to check when it does it is try tow haul mode. The cluster light will probably come on, but check to see if the trans actually changes the shift/lockup to tow/haul or not. If it doesn't, then you know the TCM isn't seeing or transmitting j1850.

That’s kinda what I was thinking the tow haul light doesn’t come on I’m not sure if that is the switch or possibly something to do with the TCM??


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[SoCalMike]

That’s kinda what I was thinking the tow haul light doesn’t come on I’m not sure if that is the switch or possibly something to do with the TCM??


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Check the orange wire in the steering column. It's known to break.

 

[dcpjfs432]

Okay I will do that


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[Rancelot211]

My lb7 was the same way. Had to solder the connection. Youtube can show you. Took me 10 minutes. My tow haul also doesn't work due to the wires. Just gonna order a new shifter.

 

[dcpjfs432]

My lb7 was the same way. Had to solder the connection. Youtube can show you. Took me 10 minutes. My tow haul also doesn't work due to the wires. Just gonna order a new shifter.

Gotcha thanks to everyone who replied I will update you on what I find out in case someone else has this problem


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