Tachometer (RPM) gauge not reading on 2004 Mercury Mercruiser 4.3L V6 TKS

[aanoi]

I read a lot of material on this subject but could not seem to find anything similar to what I have (as always the case). i realize the easiest way to get my answer is to replace the tach. but if i don't have to replace i don't really want to. also i have a tach that has the hour meter on it and i don't really want to lose that data. i've done some troubleshooting:

when the ignition is on i get 12V with the purple and black wire
when the ignition is on i get 12V with the grey and black wire.

it seems like i'm getting power to the tach but for some reason i get no reading when the engine is running. it's stuck at zero. i've cleaned all the post and re-tighten all connections and still nothing. it's highly likely the tach is bad, but i just want to make sure before i go buy a new one.

 

[aanoi]

distributor

 

[tlewis1]

Does the needle 'jump' even just a smidge when the key is turned to on? You could remove and try to jumping 12v to it to see if the needle will move..although sounds as though you've already confirmed that....sounds like a bad guage

 

[alldodge]

when the ignition is on i get 12V with the purple and black wire
when the ignition is on i get 12V with the grey and black wire.

If your getting 12V on any of the black wires you lost your ground. Black wires should be ground

 

[aanoi]

are you saying i shouldn't get 12V when i put a volt meter between the purple and black or grey and black?

 

[alldodge]

are you saying i shouldn't get 12V when i put a volt meter between the purple and black or grey and black?

No, my comment was with the understanding that you were getting 12V on the black wire and another ground.

What is your engine serial number?

 

[aanoi]

SN 0W313406

 

[alldodge]

The S/N tells me you have a TB-V ignition. So long as the motor is running, then the tach issue is either its bad or a bad connection. Ring out the gray wire from the negative side of the coil to the tach.

 

[bcboater1531]

The S/N tells me you have a TB-V ignition. So long as the motor is running, then the tach issue is either its bad or a bad connection. Ring out the gray wire from the negative side of the coil to the tach.

Sorry to jump your thread but I have the same problem. What do you mean "Ring out"?

Thanks.

 

[wellcraft-classic210]

That means to verify the wire and connections are working as intended ( No open connections, or breaks etc ) by using an Ohm meter or similar .

 

[GA_Boater]

This thread is a year old and the OP disappeared. bcboater1531 Please start a thread of your own for better visibility.

Closed.