PCM not sending out Engine Speed (tach) Signal???
07-14-2005, 02:03 PM
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PCM not sending out Engine Speed (tach) Signal??? Well I have been having problems getting my tach to work at all. I had the guage checked out and it was fine, I made sure the tach signal adapter was fine and it is. So I tested the Engine Speed (Tach) Output Signal on the PCM and I was getting no reading out of it. Also for the hell of it, I hooked up the negative of one coils to my tach wire and sure enough the tach moved with engines rpms (approximatly 1/8th what it should read, but it read it none the less). My question is, why wouldnt the computer not be giving the engine speed output? Can it be solved or fixed someway, or am i going to have to hook up my tach to the negative of one coil and have my adapter sent back and have the signal be multiplied by another 8? Also, all of my friend found this odd, but my oil pressure guage is always reading max, but when i ground the wire it goes down to zero, doesnt it usually work the opposite way? Any ideas? Also I have the Oil pressure output signal hooked up to that oil pressure guage wire and it doesnt do anything but stay at max so Im confused. Any ideas are appreciated. Thanks,
Chris
Chris
07-14-2005, 08:09 PM
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What PCM are you using? Where are you getting your tach signal from (PCM Pin #) and what converter box are you using?
If its a '99 or later PCM, they don't have a tach signal "per say". They DO have an engine speed input to the ABS/Traction module, but its a LOW voltage, 4-cylinder signal. When I did mine, I had to use a Dakota Digital SGI-8 box because it can read and interpert low voltage signals and convert to 12 volt, 8 cyl signals as needed.
If its a '99 or later PCM, they don't have a tach signal "per say". They DO have an engine speed input to the ABS/Traction module, but its a LOW voltage, 4-cylinder signal. When I did mine, I had to use a Dakota Digital SGI-8 box because it can read and interpert low voltage signals and convert to 12 volt, 8 cyl signals as needed.
07-14-2005, 09:18 PM
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No it is a 98 pcm. The wire is coming from the #35 pin location on the blue connector. The diagram I have says "Engine Speed (Tach) Output" . And it is a white wire so im positive that its the right wire.
