Erratic Tachometer

Reply Subscribe

Thread Tools

Search this Thread

Sep 5, 2017 | 10:28 AM

tnab1970

Thread Starter

Junior User

Joined: Feb 2008

Posts: 91

Likes: 0

Erratic Tachometer

1989 f150 4.9,4x4, 5 speed.
Factory in dash tach. is erratic and sticks at certain rpms for several minutes. No rhyme or reason. Any ideas as to a starting point?

Last edited by tnab1970; Sep 6, 2017 at 09:27 AM. Reason: spelling

Sep 5, 2017 | 10:49 AM

Conanski

FTE Legend

Joined: Jun 2006

Posts: 31,930

Likes: 1,499

From: Ottawa, Ontario

eradicate: to remove (something) completely : to eliminate or destroy

Congratulations for spelling it correctly but I suspect that isn't the word you wanted, I think you meant "erratic: acting, moving, or changing in ways that are not expected or usual"

I also suspect the tachomoter in your truck is faulty, it is pretty easy to change though so that would be my suggestion. You can do so by removing the trim around the dash cluster, then the clear lens over the cluster, and then the tack module will simply unplug from the cluster and you can insert another that you could source from a junkyard truck for example. I'd also suggest that you grab the whole cluster just in case the problem is with the PCB in the cluster.

Sep 5, 2017 | 12:56 PM

tnab1970

Thread Starter

Junior User

Joined: Feb 2008

Posts: 91

Likes: 0

I am a horrible speller : Yes I meant erratic, that is what i was going for when the dang spell checker thing through me off track. Crapp and I cant fix it either!

So, you think it is the tach and not a short somewhere? I had suspected a short in the harness????

Sep 5, 2017 | 05:45 PM

Conanski

FTE Legend

Joined: Jun 2006

Posts: 31,930

Likes: 1,499

From: Ottawa, Ontario

I have seen other instruments in these clusters go nuts so the gauge itself would be my first suspect. Can't totally rule out a wiring problem either but I suspect the gauge would just go to zero or to max if there was an open or short circuit.

Sep 5, 2017 | 06:36 PM

Scndsin

FTE Chapter Leader

Joined: May 2006

Posts: 12,342

Likes: 1,318

From: Central Mississippi

Quote:

Originally Posted by tnab1970

.... Crapp and I cant fix it either!

Click on the edit button of your first post, then click "go advanced".

Then you will see the title bar & you can change it.

Sep 6, 2017 | 09:28 AM

tnab1970

Thread Starter

Junior User

Joined: Feb 2008

Posts: 91

Likes: 0

OK, we will head to the yard today at lunch see if we can locate a cluster. I will post the status when installed.

Sep 6, 2017 | 12:58 PM

katjtodd

New User

Joined: Mar 2014

Posts: 9

Likes: 3

Pull you tach module out and look at the soldered connections. If you notice any connections that look dull and oxidized clean and resolder them. I have fixed several of ford tachs this way.