new member with some problems w/tach

[Waystro]

No underhood fuse box on bullnose trucks.

 

[silverrex4]

The 85 doesn't have fuse box under hood, just relays for starter and glo plugs. I havn't had time to work on the rig, but with all the suggestions I will be very busy come weekend. I will let u know how I make out.

 

[silverrex4]

Ok so I started to remove the dash, I put a volt meter on the sensor getting .2 no power, I follow the harness to another plug same thing, I pull the cluster and there isn't any power from wires and harness to cluster. Am I missing something. Does the power come from the cluster? Is the circuit board bad? Can't figure out why this thing isn't getting power. There doesn't look like any fusable links when I trace the wires back either. Any help would be greatly apprecaited.

 

[riphip]

I do wish I had finished scanning my Ford Truck Manual in at http://www.thedieselfiles.com years ago but alas I'm lazy.
Maybe will get back to it later.

Rick

 

[silverrex4]

Thanks for the link but where do I go from there

 

[laserjock]

You won't see anything if the truck isn't running. It's a magnetic hall sensor you should get a pulsed output that might look like AC. I'm not sure it's actually an AC signal though.

 

[silverrex4]

I checked the truck while it was running, but even with the sensor unplugged should there be power somewhere?

 

[laserjock]

It depends. Honestly I'm not sure if it's a magnetic sensor or a hall sensor. Hall sensor is powered. Mag sensor is not. Mag sensor does generate an AC voltage.

This is a good thread here.

http://www.oilburners.net/forums/showthread.php?54186-Testing-a-tach-sensor-and-or-gage-amp-harness

 

[riotwarrior]

With a Volt meter on AC disconnect the tach sensor plug.

Now this part is hard but check the plug FROM SENSOR for AC voltage with truck running.

Increase rpm amd voltage reading should increase as well.

No voltage at tach sensor.....sensor bad nfg junk ....

Just checked my own for @IDIoit as he was having some issues which he solved.

Start at one end and work way to dash...

JM7.3CW

 

[silverrex4]

Ok cause I was only getting .02 here and there, I sure hope the sensor isn't bad like I wrote in the earlier posts because then that's 60 bucks down the drain.

 

[IDIoit]

60 bucks for a tach sensor?
did you buy a cheap knock off?
are you positive it wasnt made in Usa China?

i usually pay 85 for the ones i have.
and yes in my situation, it was a bad sensor.

 

[silverrex4]

Check amazon, they were a motorcraft part only with the Motorcraft packaging l, and it was free shipping. I think I have more gauge problems then anything. I ordered a new circuit board for about 60 from bronco graveyard. I got the one that has the tach attached to the circuit board which I can try to not hard wire it. I have 18 pins so the tach is already there I just don't know what the guy did before me . The Guage was hardwire to the harness, I found some copper missing from the circuit board so that might be my culprit. I have the correct amount of pins from the harness so we will see what happens.

 

[silverrex4]

They have one left, better then stealership.

https://www.amazon.com/gp/aw/d/B000...Y340_FMwebp_QL65&keywords=6.9+idi+tach+sensor

 

[riotwarrior]

Ok cause I was only getting .02 here and there, I sure hope the sensor isn't bad like I wrote in the earlier posts because then that's 60 bucks down the drain.

It has to be a steady V signal .9v and went up from there iirc

 

[silverrex4]

Just waiting for the new circuit board, I praying that that copper missing near one of the pins is the culprit. I just didn't know If the harness that plugs into the gauge cluster back feeds power to the sensor and the circuit board just completes the circuit. Let you guys know, I'll try to snap some photos to show the progress.