# Need some timing help



## boraz (Aug 29, 2013)

if the car doesnt know the rippims, i can see stabilitrak and tcs in error state, but also makes sense the transmission wouldnt know what to do....so im thinking the no rippim signal to the car is the cause,

im wondering if the tach signal comes from the alternator???

check wiring from the alternator, realistically youre nowhere near the wiring while doin the tbelt, but...

also, bad ground will screw this up, you obviously removed battery cable to do the job....maybe re check it.....

also has the car had the ground cable recall done?


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## revjpeterson (Oct 2, 2013)

It sounds like the lack of tachometer input is the root problem, and all the others are symptoms. A quick, really obvious fix would be to check you crankshaft position sensor and its wiring. If you damaged a wire or broke the sensor while doing the timing belt--or maybe damaged it with the jack while supporting the engine during the timing belt change. I haven't serviced the crank sensor on these cars, so I can't tell you where to look, but start by looking in the area of the crank pulley you removed and reinstalled, and the area around where you positioned your jack to support the engine. It also wouldn't hurt to plug in an OBD scanner and see if you have a crank position sensor code, or any other code that might help you track down the reason you have no tach input.


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## v65rider (Dec 2, 2019)

Thank you for the ideas, I don't know if it has had the negative cable replaced or not. I am the second owner and I don't know what the previous owner had done. I have checked and double checked the connections and can't see any looseness in the cable ends.


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## v65rider (Dec 2, 2019)

I took everything back apart and cleaned every connection that I could find. I am not sure what it was but the problem was fixed upon reassembly.


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## MRO1791 (Sep 2, 2016)

v65rider said:


> I took everything back apart and cleaned every connection that I could find. I am not sure what it was but the problem was fixed upon reassembly.


Great news, glad that worked. I have also seen the CAN bus (the car computer network) get confused when I was using the Torque app, and shut the car off. The app keeps the ECU on when the car is off, and if I don't shut down the app and I then try to restart it, it might or might not start, and if it does will have all kind of error codes.. so it's possible you had some computer confusion as well upon restart, given you had the battery disconnected for the belt change, and it might have just re-booted the computers and cleared up the problem. 

As to prior work, can you pull a CarFax for the VIN, or ask you local GM dealer to pull up the service history, actually you might get some information from the GM / Chevrolet website by the VIN. It might be worth the effort to know what has or has not been done on the car.


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## Bsmith08 (7 mo ago)

v65rider said:


> I took everything back apart and cleaned every connection that I could find. I am not sure what it was but the problem was fixed upon reassembly.


**** @v65rider.. hopefully I can resurrect this from the dead. Exact same situation for me..saw your post and cleaned all connections to no avail..thinking I'm a few teeth off.


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