HELP No Shift Indicator Line, No Crank No Start

[07SilveradoHD]

I have a 2007.5 LMM, when the temp outside is cooler (below 60 degrees) its a hit and miss if it is going to start or not. If it is warm outside or if I get the truck to start and it warms up it will be fine the rest of the day.

Sometimes the gauges will go haywire and the shifting is acting crazy while its still cold. But once its warm and you shut the truck off and restart is seems to be fine.

Every time it does not start is is missing the line under the gears. I have already replaced the TCM and battery cables.

It does have a MiniMaxx that i did not install.

Any ideas what may be causing this? It is to the point now that I can not get the indicator line back so it will not start.

 

[Bdsankey]

When the truck doesn't start in park or show the indicator, if you put it into neutral will it fire up?

 

[07SilveradoHD]

No it wont. If the line isnt there is wont do anything in any
of the gears

 

[07SilveradoHD]

Truck hasnt started in 3 days, just went out to try it again and the line was there and the truck started. But the line keeps coming on and off and when it goes off the gauges go crazy. Abs light is coming off and on too.

 

[JoshH]

Sounds like maybe a communication problem or a bad TCM.

 

[07SilveradoHD]

Pulled the plug on the tranny today and it's full of fluid. Going to order a new one tonight

 

[Jacy_dzlguy]

Pulled the plug on the tranny today and it's full of fluid. Going to order a new one tonight

A new what?

 

[juddski88]

Sounds like a low voltage issue to me

 

[J_Stone06]

I'd check wiring harness at TCM and work back. Could wires in the column cause this sort of issue? I'm no expert in this field. Does sound like maybe voltage is too low. I'd be on the lookout for nicks/cuts in the wires though. On a separate note, I had an issue with my left headlight not working in the cold due to loose wiring/connectors that shrank in the cold and didn't make proper contact and when warm worked fine. Just throwing out ideas.

Sent from my SM-G950U using Tapatalk

 

[catmenace]

Could be the NSBU on the transmission

 

[THEFERMANATOR]

Sounds to me like possibly a gpcm issue. Sounds like your losing your data bus to me. Any module on the bus can take it down, but I remember several having problems with the terminating resistor in the gpcm having intermittent issues causing this. Check for chafed wires or shorts in your class 2, but the tricky part is catching it acting up, and checking it then.

 

[07SilveradoHD]

Well truck is still down, replaced the wiring harness and not that its cooling off at night it wont start again, No indicator line under the gears when it acts up like this. But if its sunny and 80 it seems to be fine

 

[07SilveradoHD]

Update: Checked the Ohms at the obd2 part they are reading 122 instead of 60. Latest advise has been to check wires from ECM back that it sounded like a 5V problem. Going to work on it this weekend again

 

[Rm808]

Hey did you figure out what the issue is yet?

I’ve got the same issue as you. Mine doesn’t crank or start when there’s no shift indicator light. I have to keep turning the key on and off for a few minutes until the indicator light comes on and then it starts up right away. The check engine light is not on.

I’ve replaced the battery power and negative, alternator, starter and fuse box cables.

Also changed the tcm, fuse box, starter, data link resistor and ignition switch. No luck.

 

[Ron Nielson]

Update: Checked the Ohms at the obd2 part they are reading 122 instead of 60. Latest advise has been to check wires from ECM back that it sounded like a 5V problem. Going to work on it this weekend again

There are 2 resistors int the circuit, and one of yours isn't there, at least not consistently. See attached.

 

[07SilveradoHD]

Hey did you figure out what the issue is yet?

I’ve got the same issue as you. Mine doesn’t crank or start when there’s no shift indicator light. I have to keep turning the key on and off for a few minutes until the indicator light comes on and then it starts up right away. The check engine light is not on.

I’ve replaced the battery power and negative, alternator, starter and fuse box cables.

Also changed the tcm, fuse box, starter, data link resistor and ignition switch. No luck.

No i have not and now that it is cold in Ohio it just sits where it was parked

 

[07SilveradoHD]

There are 2 resistors int the circuit, and one of yours isn't there, at least not consistently. See attached.

Thank you Ron I will check into this!

 

[Carolyn8505]

So we may have narrowed it down to something wrong with the wiring going to the glow plug mod. Moving the wiring around brings back the line and it will start. Still working to figure out what in the world is pinched or broke or shorting

 

[JoshH]

So we may have narrowed it down to something wrong with the wiring going to the glow plug mod. Moving the wiring around brings back the line and it will start. Still working to figure out what in the world is pinched or broke or shorting

You need to look at the can bus wiring.

 

[07SilveradoHD]

Update: It looks like the glow plug module on the harness side has some pins that are messed up. Any ideas on fixing/finding the female pins for the harness side?