PCM Engine Speed Signal
05-28-2007, 11:57 AM
#1
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PCM Engine Speed Signal Looking for someone who can tell me what sort of output signal is used by the pcm running to the tachometer. Want to connect a VDO gauge to a '99 pcm (C2 Red connector, pin 10). Using a LS1 engine in a project car!
Appreciate any input!
Appreciate any input!
05-28-2007, 07:33 PM
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FormerVendor
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Haven't tried it on the LS1 PCM, but on the LT1 PCM the tach output signal from the PCM went directly into my aftermarket tachometer and worked fine. I would expect the same from the LS1 PCM.
05-29-2007, 12:12 AM
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Here's what the book has to say about the tach output...
Crankshaft (4X/24X) Sensor (5.7L)
The Crankshaft Position (CKP) sensor is located on right-side
of engine, behind starter. The CKP sensor is a dual-magneto, resistive
type sensor. The dual micro switches within the sensor monitor both
notches of a reluctor wheel which is mounted on the rear of the
crankshaft. By monitoring the reluctor wheel, CKP sensor produces both
24X and 4X signals. PCM uses 24X signal to determine if a particular
cylinder is on the firing or exhaust stroke. PCM uses the 4X signal
for tachometer output, spark control, fuel control, certain
diagnostics and to identify a cylinder misfire.
Crankshaft (4X/24X) Sensor (5.7L)
The Crankshaft Position (CKP) sensor is located on right-side
of engine, behind starter. The CKP sensor is a dual-magneto, resistive
type sensor. The dual micro switches within the sensor monitor both
notches of a reluctor wheel which is mounted on the rear of the
crankshaft. By monitoring the reluctor wheel, CKP sensor produces both
24X and 4X signals. PCM uses 24X signal to determine if a particular
cylinder is on the firing or exhaust stroke. PCM uses the 4X signal
for tachometer output, spark control, fuel control, certain
diagnostics and to identify a cylinder misfire.
