Tach wiring question
06-01-2009, 02:26 PM
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Tach wiring question On the back of the display panel for the gauges, the Tach has 3 connections, labeled IGN, E, (-). Anybody know where these would be straight wired to make the tach work? I'm installing a tach in another vehicle and trying to figure out the wiring.
06-02-2009, 10:05 PM
#2
i have the service manual for my 2002,
it's vague and any repair involves replacing the whole instrument panel cluster (IPC) which leads me to believe the tach along with the speedo and other gauges is integrated with a microprocessor chip controlling everything on the IPC. the wiring diagram shows a connection to serial data, my guess is they used all the electronics on the IPC to allow for one signal wire from the PCM to the whole thing to cut costs, instead of 1 wire for the tach, another for speedo, oil, and temp. And the rpm of the engine is calculated by the reluctor ring on the crankshaft whose signal goes to the PCM (not the tach).
the IGN is +12v power to the tach, which is when the ignition key is in the run position. - is ground.
for traditional tachs the third connection is the pulse signal which comes from the negative side of the ignition coil. in the case of the ls1 there are 8 so i doubt you can simply connect it to the ground connection of one coil. you might try emailing msd or somebody who has done ignition conversions on the ls1 having the crank sensor, they might know how it works.
it's vague and any repair involves replacing the whole instrument panel cluster (IPC) which leads me to believe the tach along with the speedo and other gauges is integrated with a microprocessor chip controlling everything on the IPC. the wiring diagram shows a connection to serial data, my guess is they used all the electronics on the IPC to allow for one signal wire from the PCM to the whole thing to cut costs, instead of 1 wire for the tach, another for speedo, oil, and temp. And the rpm of the engine is calculated by the reluctor ring on the crankshaft whose signal goes to the PCM (not the tach).
the IGN is +12v power to the tach, which is when the ignition key is in the run position. - is ground.
for traditional tachs the third connection is the pulse signal which comes from the negative side of the ignition coil. in the case of the ls1 there are 8 so i doubt you can simply connect it to the ground connection of one coil. you might try emailing msd or somebody who has done ignition conversions on the ls1 having the crank sensor, they might know how it works.
06-04-2009, 03:29 PM
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When I looked at the rear of the display panel the circuit 'E' & IGN did run did run across the back tying the gauges together. The (-) was on a circuit by itself. Thanks for the info.