Completed my full gauge swap - Why doesn't the tach work?

[bighause]

From what I have read about the swap to a full gauge cluster, the tach is "plug and play", but mine doesn't work at all. All the other gauges work and I have swapped out the 2 sending units. The cluster came out of a 89 XJ and is now in my 89 MJ so I know it is compatible.

 

Is there something I am missing or something I should check?

[purplexj]

Swapped mine too, just worked . Mine is not the mechanical gauges (92) but should work.

[64 Cheyenne]

Maybe try this, although I posted this for the gas gauge, the same principle applies.

Quote, previous post, from me: " I had these same kind of problems with my cluster swap. I pulled the cluster back out. Then clearanced the plug openings (female side) with an x-Acto knife so that the male plug would "click" into place easier. Before I reconnected the plugs, I took a sharp object and pulled up on the electrical contacts (male side) to increase contact pressure. Actually my problem was with the gas gauge, after I did this I reinstalled it, no problems."

[webbjeepxj]

Also check for a bent pin, I did the swap on an SE XJ with the dummy's and the temp didnt work because when i put it in I bent a pin, confused me for weeks.

[streetjeep2.5]

Do you know if it worked in the XJ?

[bighause]

I don't know if it worked in the XJ or not, it came from a junkyard XJ. Is there a way I can test it or should I just take it out and get a new one?

[rworks]

What engine do you have? The tach for the 4 cylinder won't register right with a 6 cylinder and vice versa. IIRC, there is a potentiometer on the back of the cluster to adjust the setting.

[bighause]

It is from a 4.0 and going in a 4.0, but it doesn't work at all. It stays at 0 all the time

[mvusse]

The tach working should be plug and play. If it came from a 4.0 and went into a 4.0, it should even read correctly without needing adjustments.

 

So either you have a wiring problem, or the tach is broken.