Thread: Tach Trouble
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Old 09-08-2016, 07:21 AM
flyingfrizzle flyingfrizzle is offline
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Join Date: Sep 2012
Location: Eastern NC
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Quote:
Originally Posted by jwclbi View Post
Well here is photo of the alternator, I removed the only connection and it was very clean. I still can't find the allusive grey wire people keep referencing. The connection to the wiring harness is very clean as well along with the connections behind the tach itself. Any more thoughts?
I just realized sometimes the manual links go to the cover instead of the page listed at the end of the link. pg 173 has the diagram that will show you where the "grey" wire runs in the harness

I wont be coming from the alternator plugs, but from the ignition box #35 in diagrams. It shows a grey wire from both boxes but you want the one from the ignition ecu not the #34 fuel ecu. Hard to tell from the pic but it may be in the covered bundle your hand is on. I would start under the gauges and check the connections at the other end of the harness if you haven't done so yet then work my way back. Most bad connections are where the gauge harness plugs to the main harness at that end or the pin connector that plugs to the motor harness at the other end. The pins will get green and corroded sometimes and cleaning them and adding dielectric grease will help keep them from getting bad again. Sounds like you have done that part possibly, just make sure you check the outboard plug end and there are also plugs to the ecu's. Don't forget to check all associated grounds too. The tach signal is produced by the ignition ECM based on the crankshaft position sensor input. The crankshaft position sensor should has a good gap and read 1200 ohms. I would think if the position sensor was bad the motor would not run so you probably have one of two things.... One being the ecu that produces the signal is losing that channel (which I doubt because it is trying to work coming in and out) and the Second being a bad connection between the ecu and the tach. Intermitting issues are always hard to find. I would look at and check all the grounds on the motor as well, make sure they are clean and bonded well. It may fix the problem or keep another potential problem in the future from occurring.
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