Tach is inoperative

[ZenkiOwns]

The title pretty much says it.

I just finished an auto> 5 speed swap on my car and now my tach no longer works. I checked fuse #21 and it's good. I would usually be the first to scream SI board, but I have never had an issue with any gauges etc before.

I even ran back through every walk through I could find, hoping I missed a plug or something. I don't think I did.

The MPG meter is also inoperative, but the SI lights are still functioning. If it was the SI batteries, wouldn't these be dead as well?


HALP?

[e34john]

Does the econometer work?

[dnguyen1963]

Did you check the wire from the diff into the back of the instrument cluster?

[nando]

It could just be coincidental that your SI batteries went bad. was the car sitting unplugged from the battery for a while? the SI batteries will drain when the board isn't powered from the car.

you could open it up and check for ~3v if they're lithium batteries. I dunno about the nicads.

did you do anything behind the instrument cluster or in the dash?

Did you check the wire from the diff into the back of the instrument cluster?

he said tachometer, not speedometer.

[ZenkiOwns]

Econometer works.

It was unplugged from the battery for a few days.

I did not touch the cluster, but that really seems like the only possible culprit.

The tachometer gets signal from the ecu, not the diff.

[nando]

if the econometer works then the SI board should be fine.

there's one wire from the ECU to the cluster that sends the tach signal. it's black, 1mm, pin 9 of the (round) C101. could check to see if that's getting through. I'd find it odd for the tacho motor to die randomly. could also be a fuse but I'd think the econometer would stop working too.

[ZenkiOwns]

Did a litte research ad I'm going to go ahead and replace the SI batteries. My car is a '91, so I'm "guessing" the batteries are the CR1425OSE correct?

So all I have to do it remove the tabs from the opposite side of the board, replace with new batteries with tabs attached and voila?

I'm also wanting to replace my back lighting in the cluster as well. Almost all of them are dim.

Anyone have a good link to to a replacement walkthrough for those as well?

[blackhawkimpact]

Might be the cluster's board. That's what happen to me.

[ZenkiOwns]

Might be the cluster's board. That's what happen to me.

God I hope not.

[dnguyen1963]

It could just be coincidental that your SI batteries went bad. was the car sitting unplugged from the battery for a while? the SI batteries will drain when the board isn't powered from the car.

you could open it up and check for ~3v if they're lithium batteries. I dunno about the nicads.

did you do anything behind the instrument cluster or in the dash?



he said tachometer, not speedometer.

My bad...allergy season...my brain is in a fog.

[ZenkiOwns]

I'm about to order the batteries, but before I take everything apart I noticed the SI lights are still on. Wouldn't they be dead if it was the SI batteries?

*edited 1st post to include the above*

[dnguyen1963]

The green LEDs are supposed to be off after the engine is started. If they stay on, your SI batteries or board is bad.

[Gregs///M]

The SI batteries do not directly power the LED bulbs. So the LED indicators can continue to work even when the batteries have been discharged.

It is my recommendation to replace the SI batteries if you have any Tachometer/Econometer/Coolant Gauge inaccuracies or intermittent operation.