Buick Motorsports tachometer issue

[stg1dom]

So I finally installed my 3” Buick Motorsports tachometer in my GN. I used the white wires with the green plug behind the alternator as my signal wire to the tach. The tach does not work. So I’m thinking I may need some sort of tach adapter but not sure. Any one have any experience with these and which are you using?

 

[rag231]

I have the 3 and 5" version. When you say that it doesnt work is it stuck at an RPM position or just sitting @ 0. Does your 3" still have the reset key and cabling set up? When you applied power to it did it immediately go to 0?

 

[RmvBfrFlght]

Some aftermarket ICMs don't have a tach driver in them. Does the dash tach do anything?

RemoveBeforeFlight

 

[turbobitt]

The factory tack signal may be too low for that tack to read. Some tack devices want to see a 12 volt square wave signal and the factory signal is much lower. I had measured it at some point on an oscilloscope but forgot what the actual readings were.
If this is the case, you may be able to pull the signal up using a pull up resister. It’s a long shot but worth a try.

Read through this link on the pull up resister on the tack signal. Application is a little different but the concept is the same.

http://aeromotiveinc.com/wp-content/uploads/2015/01/TB_302_FPSCTroubleShooting.pdf


AG.


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[stg1dom]

So, the tach is stuck at like 3000 rpms. When I powered it nothing happened. It never went to zero. The cabling and key are all still intact. This was literally brand new in the box.

 

[stg1dom]

I didn’t try but can I measure the tach output behind the alternator with a multimeter?

 

[turbobitt]

So, the tach is stuck at like 3000 rpms. When I powered it nothing happened. It never went to zero. The cabling and key are all still intact. This was literally brand new in the box.

Are you sure it’s getting key power?


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[rag231]

The 3 key positions are Erase, Tach and Memory. Red and white wires on the gray connector and black and white wires on the black connector , I cant see other wires if any the way that it was laying. I am looking at some older pictures that I had before mine was installed.

 

[stg1dom]

Well after looking further into this turbobitt was right. I guess when I reinstalled the trim under the steering column the power wire must have pulled out of the ign 2 spot in fuse block. I feel like a dumbass but it now works perfectly. Thanks for all your suggestions.

 

[turbobitt]

The strong hint was that the needle didn't go to zero with the key on.
Glad you got it working...
AG.