I thought this would be an easy fix by replacing the CPS.But unless I have a out of box failure, still no fix. Any ideas? ABS works fine, RPM shows up on scan tool for engine OBD-II. Replaced cluster as well. All fuses check out.
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02-10-2009
I thought this would be an easy fix by replacing the CPS.But unless I have a out of box failure, still no fix. Any ideas? ABS works fine, RPM shows up on scan tool for engine OBD-II. Replaced cluster as well. All fuses check out.
02-10-2009
As far as I know, the only thing that could cause the tach to fail is the CPS as the signal from the tach comes directly from the CPS. That said, it could be a wiring issue too, maybe the wiring is messed up in that harness. I suppose it could be something with the Ignition Control Module as well since all the wires from the CPS go directly to the ICM, but I have never seen an ICM fail in that manner, I have seen a CPS fail that way.
The wiring that connects the CPS, Camshaft Position Sensor and the ICM is all one harness and down around where the CPS is a fair amount of heat from the block and such and that harness can become brittle and Im sure the connector itself can get that way as well, so there could be issues there.
Both spark and tach signals originate at the CPS then go to the ICM so I cant see the issue being anywhere else. The ICM does generate a Low and Medium resolution engine speed (tach signal) but I cannot tell from the schematic if the CPS is responsible for both, my suspicion is that it is not because two of the four CPS wires are for spark and tach, the other two are voltage and low reference, so that tach signal you are seeing is something from the transmission or one of those other engine speed signals.
02-10-2009
Thanks, I'll have to disconnect the harnesses and check the wiring with the ohm meter for continuity. Before I replaced the CPS I did re-wrap the sensor pig tails and connectors and found no damage of course at that time, so I guess I must dig deeper.
02-10-2009
i've been having the same exact problem too, trac off light randomly comes on and stays on, and the rpm tach just dies but the mph tach works, after i turn the car off and turn it back on it works perfectly. idk why it does this tho
02-17-2009
I have good continuity between the CPS and the coil pack. I am in need of a good wiring diagram to see if problem is between the coil pack and the next system or the coil pack itself. Anyone have a diagram in pdf?
05-23-2009
bump same problem
07-27-2009
found out the problem it was the crank shaft sensor my prix has been trouble free now o and btw the old sensor had a gold made in China sticker on it, that was probably the reason why it failed lol
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