# Need some help with a dead tach



## brooklynboy (Aug 5, 2014)

I did a little research on this previously but it's still being a PITA. I have a 98 GXE auto with 167k. From the time I got the car a few months ago the tach didn't work. It would always read zero and not budge. I replaced the cluster and that didn't solve the issue but created a new one. Now my speedo sits at zero as well. I screwed up the speedo when I tried to swap my odo into the cluster but the car is now throwing P0725 for engine speed signal. Could my screw up have done this?

For the real problem of the tach, I probed the black & white wire off the distributor & got 2.4v at idle but I have no baseline reading as to what's normal. I also probed #3 on the ECM harness, got nothing & the same for #24 on the ECU harness. From looking at the FSM, I should get .5-1.5v when running the car (drove it with probes hooked up around the block at about 1/4 throttle)

Before anyone asks, I run Torque with a ELM327 through the OBD port & I get RPM's and speed and they are accurate.

Can anyone help me out here?


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## brooklynboy (Aug 5, 2014)

Did a little more digging today. I have continuity between terminal 3 on the ecm and terminal 24 on the tcm. From terminal 24 i have continuity to terminal 35 on the cluster, am i right in deducing that the ecm is at fault?


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