Tach

[Ottoparts]

My tach has gone lazy on me.
At an idle, it reads 0 rpms. Any rpm above idle and the tach works and appears to be as accurate as normal.
Would this be a gauge issue or a pick up issue?
Anyone else have this problem?

Thanks

 

['94IDITurbo7.3]

time to investigate the tack sensor. the wires could be bad, sensor could be dirty or bad. it is the big 1" nut next to the oil fill with two wires going into it.

 

[Devon Harley]

Grounding issue under dash or you need to get a new tach sensor 51.37 last week at dealership but I have an account so maybe 75 for you idk

 

[boxathey]

Do you have to remove dash or instrument cluster to check the ground ?

 

[Jbevs]

Bump for the tach ground location please.

 

[Ataylor]

I was having an issue with my tach not working on my 1987. The wires going to the tach sensor on top of the timing gear cover were cracked where they entered the sensor. It was too close to the sensor to repair. I bought a new sensor from Ford for $79.19 Part #E5TZ-17B384-A (I think that is a "5", but it could be an "S"). Fixed the problem. I haven't checked, but maybe the sensor could be found on RockAuto. They sometimes carry Motorcraft parts.

Archie

 

[G. Mann]

I had the same problem on my 92, pulled the sensor pickup, cleaned it, and the tach would "kinda improve" for a while.. then go back to reading low and never moving at idle..

Replaced the sensor at the engine.. problem instantly fixed...

 

[kc0stp]

As stated above just replace the sensor, 98% of the time thats the problem (either the sensor itself or the wires from the connector to the sensor) and for the record yes I know that first hand, when I got my truck tach would only work when on the throttle.

 

[icanfixall]

Tach senor is your problem plus.... That E4OD trans depends on this senser working correctly. Spend the money or risk ruining the trans. Its that important to have a properly working tach on the E4OD trans.

 

[Jbevs]

I bumped this thread and have a zf. I'm fairly sure I have a grounding issue, as the same time my tach stopped working, my coolant temp and fuel gauge both started working. My temp gauge isn't even hooked up.

 

[OLDBULL8]

The tach sensor generates a very low voltage at idle, as the RPM increases so does the voltage IIRC max is about 5 volts. It could be that your connector from sensor to harness is corroded, if it's corroded, that is a resistance.

 

[jaluhn83]

Yep, check the connections and wiring. Also remove the sensor and make sure the face is clean. They'll collect sludge and chips which effectively shorts out the magnetic field that make it work. Make sure it's fully tightened and the boss and sensor threads are clean.

The closer the sensor is to the gear the better the signal. Anything keeping it out away from the gear or decreasing the signal strength will cause problems. These sensor are not well setup for a reliable signal. Ideally the face should be 0.010" from the gear, but from what I could tell on my truck it's 0.060-0.075" away. To some extent I'm sure that's required due to production tolerances and needing to account for variable sealant thickness between the gear cover and block. Signal strength is an inverse square function of clearance, so the small difference is pretty significant.

 

[RavenTBK]

Bumping a related thread. The tach sensor on top of the cam cover... it is a standard lefty-loosey threaded piece correct? Mine is seemingly welded to the cover, and I am afraid of breaking something by putting too much pressure on it. Its putting out .31vAC at idle, but then randomly drops to .06vAC for a few then back up without adjusting engine rpm. I agree its gone bad on me.. but unsure exactly how it removes.

 

[Jbevs]

Correct, standard threads. I had to get on it pretty hard to loosen it.

 

[MedicMoe]

OK, I've read this and searched all over for installing a tach onto my truck. It had a standard gauge package without a trip meter, and no tach. I went to my local pick and pull, and found a real nice gauge cluster with a trip meter and a tach. I pulled it out of the truck, as well as the sensor. brought it home and tried to hook it up. all of the other gauges work just like the original, with the same readings, except the tach sits on 0. Am I missing something from the donor truck? the truck in the yard was an auto, I swapped out the gear indicator on the gauges for the one in my truck (t-19). and i cleaned the sensor, installed it to the correct location, and plugged it into my factory harness. I was always wondering what that big plug was for. the sensor does have an area of exposed wire, so is there anything else i can check or missing before i buy the $80.00 sensor?

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