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No tach output

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Old 01-05-2009, 06:06 PM
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Default No tach output

I have checked the wiring for the cam sensor and tach, no problems there. I had a P0343 cam sensor code, I found that I had a broke wire in my harness, I fixed that, it cleared the code but still do not have a tach.

Any ideas?
Old 01-08-2009, 12:08 AM
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Any help
Old 01-08-2009, 08:40 PM
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Do You have 12V and ground at the cam sensor plug?
Do you have continuity between the signal return wire at the cam sensor and the PCM????
Just fixed a truck a couple of days ago that had no tach and cam sensor codes, found a lack of 12 volts at the cam sensor!!!

Mike
Old 01-08-2009, 10:05 PM
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I just verified 12vdc at the cam sensor 12v reference, good ground on the low reference and continuity through the signal line to the pcm all checked good. Re-checked 12vdc present at tach, good ground, also continuity from PCM C2 pin 10 to tach, no issues. I am stumped, I think I am going to pull the tach out and bring it into work, put it on my waveform generator and see if I can get it to work.

I noticed the shift light only comes on at 0 with the key in run, engine off. When the key is cycled on it goes to the selected shift point but the light does not come on, so i believe it may be the tach itself. I do not remember if the shift light comes on before every start up.
Old 01-08-2009, 11:20 PM
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no the shift light shouldn't come on at startup at least on my autometer tach

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Old 01-08-2009, 11:22 PM
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Okay, cool thanks appreciate it
Old 01-11-2009, 11:46 AM
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HPtuners reads and displays hi to low signals from the cam sensor so I know the cam sensor is working and the wiring is good. The tach line out of the PCM has no signal, I will be replacing the computer I suppose
Old 03-22-2010, 10:12 PM
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has anyone figured this out yet...jeez!!! got the same problem!
Old 03-25-2010, 10:56 PM
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If this is an engine swap or you are using an aftermarket tach and you are using an 03+ pcm you may need to do a pull up resistor. http://www.lt1swap.com/lsx_tach.htm

My tach did not work until I did this circuit, now works like a champ.
Old 05-14-2010, 09:25 AM
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Bringing this one back. I've got P0342 Low Voltage Cam Position Sensor, and no tach. From what I've already learned in this thread, I'll check the wiring for good voltage, but what about the tach!?!?!



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