Follow the wiring down away from the gauge to look for either opens in the cable(s) or shorts to ground.

 

How did you remove the solder where the buzzer was attached? Didn't leave any behind or possibly come in contact with any other soldered parts on the board? Did you mess with the needle in anyway?

 

It wouldn't surprise me to find that removing the door buzzer causes the problem (kidding here...at least a little).

I recently did the map light mod and forgot to pull the fuse first. That's the same fuse that the clock runs through. With the fuse blown/removed, the clock resets to 1:00 upon startup (power outage type condition), then dimly glows and runs with the engine on. How can that be when the fuse is removed and there should be zero power going to the clock? Once I replaced the fuse, everything was back to normal.

So, there's obviously some weird wiring going on in these trucks.

 

I recently did the map light mod and forgot to pull the fuse first. That's the same fuse that the clock runs through. With the fuse blown/removed, the clock resets to 1:00 upon startup (power outage type condition), then dimly glows and runs with the engine on. How can that be when the fuse is removed and there should be zero power going to the clock? Once I replaced the fuse, everything was back to normal.

So, there's obviously some weird wiring going on in these trucks.

There is actually 3 power connections to the clock.
1) via the dome light fuse directly to the battery. This supplies power to keep the clock running with out the display on when you turn off the clock.
2) via the ACC. fuse. When there is power here the display is on.
3) via the Tail relay. This controls the dimming when the lights are on.

So when you applied power to the ACC power input but not the normal power input connected to BATT the module was partly powered up.

 

Well that makes me feel better. Although it seems odd to supply power to something from multiple sources. One would think that if the clock shorted out, then multiple fuses will blow rather than just one.

 

Well that makes me feel better. Although it seems odd to supply power to something from multiple sources. One would think that if the clock shorted out, then multiple fuses will blow rather than just one.

It's not powered from multiple sources, as there is only one 12V source that actually powers the clock itself. The ACC is switched power to light the display and the rheostat adjusts it for dimming, all as noted above.

 

Phoenix - I took the cluster out to fix the tach - taking the buzzer out was just something I decided to do while I was "in there". The tach is doing the same thing it was doing prior to taking out the cluster.

 

Phoenix - I took the cluster out to fix the tach - taking the buzzer out was just something I decided to do while I was "in there". The tach is doing the same thing it was doing prior to taking out the cluster.

Could you possibly take a video of what's happening and post it on youtube?

 

Could you possibly take a video of what's happening and post it on youtube?

I might could do that, it sounds like something is "in there" turning and catching every now and then, clicking, and the needle "bumps" slightly.

It stops doing that I guess once it is cranked - or maybe I just can't hear it then. It's not that loud really - I notice it so much because I'm looking for it now.

Very strange.... Let me look into the video. What other connections should I look at that would be related to the tach only - every other instrument in the cluster is working as advertised.

Thanks again for any help.

 

:confuseda:UPDATE - turns out warm weather has made my tach work again pretty dependably. Any ideas out there as to why my tachometer was intermittent during the winter only?

The funny thing is I have an odometer gremlin in my 93 rx7 - it works all the time in the winter and goes intermittent in the summer/warmer weather.

Pretty funny... I guess I'll do a compare/contrast of the two systems to see if I can come to a conclusion as to why they behave opposite of each other. Just kidding - not that worried about it!

 

had something like this happen to another truck i had.... turned out to be a spark plug wire shorting to the block....