TACH CLUSTER UPGRADE ISSUE

[Mhfco6]

I have a 1987 F150 and I swapped out the cluster with a tach. Been keeping my eye out for one from a manual/300. The switch was plug and play and went perfect. After admiring the tach at idle and a few revs the temp gauge pegged out hot and the engine light came on. I ran a jumper from the negative battery post to the sending unit but no change. Any idea to fix this?

 

[Mhfco6]

I have a 1987 F150 and I swapped out the cluster with a tach. Been keeping my eye out for one from a manual/300. The switch was plug and play and went perfect. After admiring the tach at idle and a few revs the temp gauge pegged out hot and the engine light came on. I ran a jumper from the negative battery post to the sending unit but no change. Any idea to fix this?

Took it all back apart and now it works fine. Took it down the road and convinced this is the best thing I’ve done to the truck. Not sure what fixed it but kickin’ now.

 

[RonD]

Temp wire could have grounded out in the wiring behind cluster, that would cause temp needle to go to HOT, same as grounding the temp sender wire in the engine bay