Tachometer stopped working

[mr cribb]

92 5speed 206k miles..... as the title says, tach stopped working. I searched a few different variations of the title w/ nothing helpful... the posts are there but no serious answers.

The rest of my gauges work just fine, it's only the tach that stopped working. It worked just fine at 530 this morning to work, and on the way back home at 730. When I left the house at 9am no tach. No CEL or anything. Doesn't the tach run off the crank sensor?

Any help is appreciated.
Thanks in advance,
Jeremy

 

[cloaked_chaos]

You may have a broken solder joint. Does the tach stay at zero or does it stick at 3,000rpm?

 

[mr cribb]

Stays at zero unless I hard accelerate the it will hang at 3-3.5k for a second or two, before dropping back to zero.

 

[snoranger]

Doesn't the tach run off the crank sensor?

Any help is appreciated.
Thanks in advance,
Jeremy

Not exactly.

The crank sensor sends its signal to the Ign Control Module. The ICM sends out the tach signal on the IDM (Ignition diagnostic monitor) wire. Which goes to the computer, tach, and data link connector.

 

[Roadrunner777]

I'd check out the 3,000 RPM tach fix thread, and look for other solder joints. Actually, I'd probably just get an iron and solder and reflow ALL the joints.

 

[mr cribb]

I pulled the tach out and re-soldered the broken spot, however, the circuit board is burnt. Looks like a junkyard tach is in order.

It even smelled burnt, and you can see the burnt spot.