Tach Sensor

[rdoimages]

I'm questioning my tach. It will drop to 100 at idle at times, feels like the idle is a bit low, but not loping like its at 100. It's not really bouncing much, just seems to be off. With the gear vendors engaged, it's showing right around 1000 at 55 and only 1150 or so at 65. I haven't had a chance to check for a tag on the rear, so I don't know the gearing. It runs amazing, just find it hard to believe the tach.
It it possible for it to be wearing out or do they generally just outright fail?
I hate to spend $85 for a new one and then find out there isn't anything amiss with the old one.


89 F-350 sc 2wd DRW 7.3 ATS 088, C-6 with Gear Vendor and a rats nest of wiring that was free with purchase.
00 Excursion limited, 6.8 4x4
2001 Jeep Cherokee Classic Sport 4x4 4.0 auto

 

[riphip]

Likely the tach sensor on the IP pump cog cover. Driver's side of cover w/2wires protruding. Connects to wiring harness above Passenger side valve cover behind alternator (on my '86)

Rick

 

[rdoimages]

I might not have been clear, I know the issue isn't the tach itself. Do tach sensors wear out slowly or do they generally just fail outright?


89 F-350 sc 2wd DRW 7.3 ATS 088, C-6 with Gear Vendor and a rats nest of wiring that was free with purchase.
00 Excursion limited, 6.8 4x4
2001 Jeep Cherokee Classic Sport 4x4 4.0 auto

 

[G. Mann]

My 92 was acting the same way.. Pulled the sender on the IP housing case, cleaned the face of the magnet and it worked for a while longer, still wasn't satisfied it was giving a good signal to the tac because the readings seemd low.. Replaced it with a new one.. fixed the problem instantly..

Worth spending the money for me. I now drive by the tac more than the speedo.. long as I keep the engine in the "sweet spot" RPM wise.. fuel economy improves.. likely saved the price of the sender several times over.. by now.

 

[BDCarrillo]

Take a look in the tecg section for a how-to on using an $18 off the shelf sensor.

With my trucks and about 5 sensors on hand, failure symptoms included low readings, no readings, and low/no idle reading. They don't appear to fail in a consistent manner.

I tested them with an IP gear in a drill press, and a spare tach wired up.

I did rescue one sensor by hosing it out with brake cleaner through the wire holes and then sealing them up with silicone. Moisture intrusion seems to be the main sensor killer.