1989 F-250 tach problem

f-250_Diesel · 04-02-2007, 07:51 PM

Today i finally had the chance to work on my truck to fix my tach. It hasn't worked since I bought the truck a little while ago. I went to the scrap yard and picked up a used tach to see if that was the problem, no. I used a test light to check power to the terminals were the tach plugs into, I've got power on one prong, the other three are dead. I'm not to sure which ones are to have power and which ones dont. Another thing is when i turn the key to the on position the needle jumps a little bit. I just cant seem to figure it out.

Sorry for the story but any help would be great.

Justaddit · 04-09-2007, 01:44 PM

This sounds exactly like a problem I am having with an '89 FSuper Duty Diesel that is in my shop right now. I will assume that you have a manual trans since you said nothing about a shifting problem. I will make a deal with you....whoever finds it first has to post it here, ok? I have replaced the tach sensor and tried an ECM with no luck. All of the wires check good and the terminals are tight.......I will just keep looking, I guess.

f-250_Diesel · 04-11-2007, 07:27 PM

Quote:

Originally Posted by Justaddit

This sounds exactly like a problem I am having with an '89 FSuper Duty Diesel that is in my shop right now. I will assume that you have a manual trans since you said nothing about a shifting problem. I will make a deal with you....whoever finds it first has to post it here, ok? I have replaced the tach sensor and tried an ECM with no luck. All of the wires check good and the terminals are tight.......I will just keep looking, I guess.

Well mine is automatic but i am having a short shift problem other than that it runs fine.