Long story short I ripped the harness under the driver side fender. I repaired the harness now my tachometer doesnt work.

Everything else work fine, gauges work fine, fuse is good. So I hook up my laptop to my standalone and the computer shows in real time data the rpms.


What could be my problem?

 

The tach solder point is a common weak spot that fails. Possible that it came loose/broke when the harness got yanked?

Im in a similar spot. Tach randomly either works or goes crazy. PFC always works fine. 19yr old connections
I hate taking guage pod/panel/clusters apart

 

Not sure how the drivers side harness affected your tach unless it pulled the tach point or a wire leading to the tach. I thought the tach got signal from the ECU...

Tach signal comes from plug B1-01 on the ECU...Yellow/Blue to the tach input...

 

Your stand alone will read RPMs from the ECU directly so that will always be correct.

 

So should I find the B1-01 on the ECU...Yellow/Blue wire and stick a test light or multimeter to see if I am getting a signal?

What should I be looking for considering the tach recieves the rpms by waves how can i test it.

 

A test light or multimeter will tell you if an electric current is going through but won't tell you anything about the quality of the signal.

I'd test it at the tach and at B101 to see if there is a break anywhere in the wire and examine the tach solder point on your cluster.

Workshop manual isn't very helpful with this as their solution is to replace the tach...

 

hahah Yeah well I will remove the tach this weekend and inspect it . I also read on a few threads while searching that the internal capacitors go out and its a very easy soldering job to fix.

I will keep the thread updated lets see if I can fix this new issue.

 

i had the same issue on my e11 a few months back come to find out it was a purple and black wire that needed to b grounded to the chases. once i did that boom worked like a charm.

 

Alex, remember that u removed the ecu and put it back in. it could be that theres a ground wire or something disconnected down there...

 

my tach is going crazy right now, sometimes it reads fine and sometimes it jump a 2000 rpms above what is indicated on the pfc commander.