Engine/Transmission (1998.5 - 2002) Tach=0 RPM

[Turbo Tim 1]

Ok a few times over the past couple of weeks my tach has stayed at zero after start-up but it doesn't give a CEL or any running issues. I changed out the cam position sensor less than 40,000 miles ago but the lack of other problems leads me to believe it's not the CPS. Has anyone seen the tach go bad in the instrument cluster? Like I said, it doesn't have any issues other than the tach being dead.

 

[DBraunig]

Tim,



More than likely the crankshaft position sensor is goind south. have you scanned the ecm for codes? Some codes won't turn the cel light on immediately.



Dave

 

[ToolManTimTaylor]

He has an 01 No crank sensor. Tim I have to say you were right on with the cam sensor. BUT when a cam sensor goes bad it will produce a really cruddy running truck. Mine did anyway. However I thought that the Tach was driven from the input the VP44 sees off the toner ring.

 

[DBraunig]

Sorry, i missed the model year. We had a truck doing something similar several years ago. The cam retainer bolts had come loose and would allow the came to walk forward enough to lose the signal for the cam sensor. I don't know if this is the case with your problem. You've got to pull the front cover enough to inspect the cam retainer and bolts. just an idea.



Dave

 

[Turbo Tim 1]

Thanks guys, I'll check the cam position sensor conection, I replaced the CPS less than 40k??? ago. I hope its not the bolts on the cam gear. When my CPS went bad before the truck ran bad, this time it's fine. Actually for the last two days the tach has worked fine also. I just know it's going to rear it's ugly head all of a sudden.



on edit: I was thinking the CPS gives the tach signal and the VP uses it's own signal????

 

[Turbo Tim 1]

Here is what I've found out, my tach stayed at zero when I started the truck a few days ago, I tapped on the gauge cover and she popped right up to idle rpm. I've repeated this situation a few times now so I know it's the actual tach going bad and not a sensor. Has anyone ever had the dash tach go bad?