Dash not working properly

dastrups

Well-Known Member
I have noticed several things not working properly on my dash. Speedo, mileage, and coolant temps not showing at all. Rpms and other things work fine. I have a brand new coolant temp sensor and a brand new sensor on the transmission for the Speedo. Any ideas?
 

Gtstorey

Goblin Guru
Did you check the resistance on the VSS? My original and the new one on the transmission that I bought from DF were both out of spec. The replacement I bought was in spec. I don’t know for sure that it was a problem since it turned out to be a bad stepper motor on the speedometer.

I would bet you have a wiring problem though and need to start tracing. Probably two different issues though since the data wiring seems to be working.
 

Gtstorey

Goblin Guru
A bad VSS might should show a code although I’m not sure? Tracking down the speedometer trouble shooting in the service manual is a little iffy since it is several different sections.
 

Ark :D

Goblin Guru
Mileage comes from the BCM, so if you're not seeing mileage in your cluster, to me, it would indicate a problem in the wiring between your BCM and cluster. Not very helpful, I know...
 

Gtstorey

Goblin Guru
On some of the transmissions, I think the reverse sensor and the VSS have the same connector so make sure they aren’t swapped.
 

Ross

Goblin Guru
Is the GM LAN working at the OBDII port? (Can you pull the engine codes)
This test will tell us if the data is flowing from the PCM & BCM, to the OBDII port.
 

dastrups

Well-Known Member
I get P0119 and P0128. But the engine and sensors are all brand new. Even the fuse box is new. I would say my wiring is probably goofed up somewhere. I don’t really have the expertise to know what to look for.
 

Gtstorey

Goblin Guru
Since the first code is an intermittent signal, let’s start with the wiring diagram and few checks. Inspect the wiring from the sensor to the ECM. Especially the connector on the sensor. If that checks out good check the resistance across the sensor to the table included. If that checks, you should get pretty close to the same readings at the ECM connector. If I need to walk you through it a little more let me know.
 

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