Is this a common problem with these trucks? '94 Pickup 22re manual 4x4.

After it warms up when it idles it sometimes reads 0 RPM. If I rev it a bit it goes up but then I let off the gas and it drops down to 0 again. I'm thinking tach or tach cable. The motor itself seems to be running normally and doesn't at all feel like it's about to die, it actually feels like it's at a normal RPM.

Just seeing what you guys think I should start with. Is removing the tach gauge a project? Any tests I can perform to see what the actual issue is?

Thanks,
Dave

 

94 is electronic, sounds like the wire to your coil is flaky, or you have a cluster from a v6,

 

The tach wire goes to the igniter, not the coil (same signal, but if we're looking for a wire, that's where you start).


The same signal is present on the "tach" connector right next to the diagnostic connector. If you could lay your hands on a '90s era electric (not inductive) tach for which that connector is designed, you could see if you get the same drop-to-zero there.

 

Interesting, thanks guys. If it wasn't for you I'd be searching for hours for a cable, haha.

Scope, so you're saying I could get a tach and plug it in to the harness as a test? That could work, but I'd need to find a tach. That really seems like my only test at this point. Unless I see changes while jiggling the wires...

 

It's not likely to be the igniter if the truck is running. So it's most likely the meter itself, or the wire from the igniter to the meter.

Trying to read the tach signal at the diagnostic connector is really a test of the igniter (which shouldn't be an issue) and the wire immediately at the igniter. It doesn't yield much, so I'm not sure it's worth finding a non-inductive type meter just for that.

If wiggling wires doesn't make an immediate difference, I would remove the combination meter (instrument panel) and see if I could measure the signal right at the meter. If I could read it there, it would mean the meter is bad.

Sorry, none of this is likely to help you much.

 

Ah, got ya. I'll post results of my findings this weekend. And it does help, haha.

Thanks

 

On my way to work today I tried smacking the dash right above the tach when it was reading zero RPMs. All needles jumped a bit which was predictable. But after that the tach fluctuated a bit and then went up to 750 RPMs. To me that seems like a viable test which may point to the tach gauge itself or the connection or the wiring in close proximity.

 

If it dont work, wack it a few times lol

 

earmuffs children

That's what I say to my girlfriend, ohhh!

(I'm actually single )

 

Little update. After I smacked the dash it seems to be functioning normally, haha. I will address it if/when it becomes more of a problem. When that time comes, I'll likely remove the dash and replace the tach with another one or just check/test connections.

Thanks for your help, everyone.

 

Is smacking the dash is getting it to work again, I would try just reseating the connectors to the gauge and see if that fixes it. Try the easy things first.

 

Thanks Terry, it would be smart to try that before ordering a new tach. If my problem persists, I'll do the easy things first, ha.