my tachometer (tackometer?) stays at 2500, but when i rev the truck it will go past 2500 to whatever the truck is revving at, but then goes back down and stays at 2500. i think it might be some type of short or electrical problems. im not sure if it is accurate, either. what should these trucks be reving at when at the top of a gear? any suggestions on what could be causing the problem? 1992 f150 4.9 i6 standard. all help is appreciated. -thanks

 

Is the truck itself idling high?

 

I'm afraid your tach may be shot. There was a mechanic on another site that said tachs like this were shot. My 1988 F-150 with the a same engine and transmission won't drop below 2200 with the engine running, it shows faster as the engine is revved up but I'm sure mine registers too fast. LMC truck sells new tachs for 1992-1996 Ford trucks but they're pretty expensive, around $220 if I remember right.

 

i dont think the truck is idling high. i dont need the tach to be able to know when to shift, but it is cool to have a working tach. is there a fuse for the tach? where are the connections for it? im pretty sure its an electrical tach, rather than a cable. if the tach is completely shot then i guess ill leave that for last and fix it in the future.

 

i just put a oem tach in my 93 f150 5.0. i bought the whole cluster at a local junk yard for $35 +tax. so get ahold of your local junk yard. you can also keek your speedo in your truck now and install it in your new cluster.

 

I had the exact same thing with mine 2500 Rpm reading @ idle then tach reading normal when revs above 2500. I swapped out the tach. and I was good to go. I got the whole cluster off e-Bay for $39 delivered. So now I have some spare gauges,plus the cluster clear lens cover was perfect so I used it too, that was a bonus for me

 

Oh, I forgot to say you can only use a 92 or 93 cluster . Others had an Air bag indicator light and will not work. 92-93 did not have that indicator light it does matter. So make sure you only get those model years. Best to Ya "92"

 

Well then sounds like a wiring issue! Good luck man!

 

My 92 F150 with a 5.0 has been doing the same thing. It worked for a week or so last month but then went back to the old ways. I bought the truck in october but haven't got around to the tach. yet. Just got done with a new fuel tank and fuel pump today. Anyway right after I bought the truck I purchased a set of Ford manuals from Helm.com. Here is some trouble shooting info from the manual. Tach is inoperative or erratic. Check for loose wiring connections in the engine compartment or at the instrument cluster. If wiring looks good, remove the instrument cluster. Make resistance checks at the connector that hooks into the cluster. Pin No. 3 to ground 1ohm or less. Pin No. 10 to ground 1 ohm or less on a V8, should be open on a 6 cyl. Pin No. 9 to the neg terminal on the coil should be 1 ohm or less. Then check for about 12 volts at pin 13 with ignition on. Then check for damaged circuit board if that checks out good then replace tach. Thats from the body, chasis, electrical Ford book. The EVTM says to check resistance between pin 9 and 11 (T/Y) wire to the ignition coil for 10 ohms or less. I plan on doing some trouble shooting on mine before I replace it. Hope this helps.

 

Is the trouble shooting info in it better than Haynes & Chiltons.

I just looked for for bad wiring & connections at the coil ,the engine compartment & at the instrument cluster & board. They were good.
Then I swapped out the Tach. and it worked out for me.

But, I would have liked to gone farther w/ trouble shooting. So would you say your manuals are better with all around info? Is it a Ford Factory Serice manual or another manual better than Haynes /Chilton? And if so can i still get them.

Reason, I ask that is because I use Harley Factory Service manuals and for H/D--m/c's they are hands down the best for them.

 

You answered your own question.

 

Yes the Ford manuals are way better. You can still get them through Helminc.com I got my 92 truck ones last oct. Bought ones for my 93 mustang last year too.

 

I "think" that the F250HD and F350 till 97 used the non airbag cluster.

I'm only basing this thought on personal knowledge of an "never touched" 97 F 250HD that has the 92-93 cluster and is OBDI controlled.

This may not be entirely true, though, so do your homework before purchasing.