OEM Tachometer stopped working a while back...

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Jul 18, 2013 | 01:09 AM

SideWinder4.9l

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From: Eastern Ky

OEM Tachometer stopped working a while back...

I swapped the instrument cluster w/ a tach from a 1993 F-150 a while back and it all work swell until a couple months back..

Perfect tach hand movement, on target with rpm in relation to throttle position...

And no skipping, etc.. Then one day I started the truck up and the hand barely wiggled... Crap.

Then a day or so later, not even the faint wiggling when I'd turn the key on.

Fast forward to tonight, when I finally started fiddling around with it, after watch Techtron1's video on a similar issue.

Here's some ohm testing I did on the circuit board.

Anyone have any insight on this issue?

Another note:

With the Key ON, the IGN port doesn't get ANY voltage, it actually registers as like -30v on my tester.
With jumpering a wire to the IGN port, from the Green/Red wire for a 12v source, no change, not even a wiggle from the tach.
The Signal wire is getting 12v at the cluster port.

Any help at all will be much appreciated, as this is a really irritating thing.

Jul 18, 2013 | 01:59 AM

eagle275

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From: Umicorn UtopiaFantasyLand

hey Sidewinder, jusy making a comment here - I need some help with my 1996 cluster project and need to find on this forum who is the best gauge/instrument cluster guru fixer/rebuilder on clusters here @ forum. You have an impressive test going there, sorry I can't help much, but willing to learn! Definitely looks like you are doing alot of work. Keep the shinny side up! Good luck !

Gotta make a run on a new International Silver Eagle to Texas and will have my ipad to stay with forum.

Jul 18, 2013 | 04:00 PM

RIKIL

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Sidewinder, I'd just get another from the pick a part.

I am not an electronics tech but I was told it isn't accurate to measure the resistance of components while they are attached because the circuit they are attached to may throw off the results.

I had a truck where the speedo had 3 transistors literally fall off, oh, absinthe large 48 pin IC came off halfway as well. I've also heard of this from others as well, just FYI ,might be related

Eagle - start a new post and ask your specific question

Jul 18, 2013 | 04:36 PM

77 1/2 F250

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Quote:

Sidewinder, I'd just get another from the pick a part.

I agree. Probably cost less in the ling run too.

Robert

Jul 18, 2013 | 05:56 PM

Tectron1

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From: Wanatah In,

I am assuming that you have already re-flowed the solder on all of the connections, with no luck. Without a schematic things get more difficult. You wont get an accurate reading on most of the components unless you de-solder one leg from the PCB in order to remove it from the circuit. Try cleaning the post that go into the cluster with a scotch bright pad, my temperature sensor flaked out and it ended up being a poor connection to those posts.

Jul 18, 2013 | 10:14 PM

SideWinder4.9l

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From: Eastern Ky

Quote:

Originally Posted by RIKIL

Eagle - start a new post and ask your specific question

He's fine, I've already PM'ed him.

Quote:

Originally Posted by Tectron1

I'll check that.

And no, I haven't re-soldered anything because the only solder I have, has acid in it.

Also, I checked all those Ohm loads by touching the pieces of wire on each resistor, etc... Never did it via the circuit board.

Shouldn't the cluster be getting 12v on the IGN position of the gauge?

Jul 19, 2013 | 07:48 AM

Tectron1

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From: Wanatah In,

OK, once you re-solder everything its almost sure to work, If you can post a close up pic of the solder side of the PCB I can probably show you specific connections that are bad(the brown heat stressed areas of the board), although I would just re-solder them all. You can get a solder iron and some solder from radio shack for under 20 bucks last I checked.

I would think that you should be getting voltage to one of the gauge pins, but there are a couple times Ive been working on equipment blindly without a schematic that had no measurable voltage at the supply pins, but functioned once I replaced the module that goes there. Id re-solder, plug it in and see what happens.