My truck seems to be experiencing either an alternator problem or a problem with the computer. At least that's my very un-expert analysis.

When I try to start the truck, the engine will turn over a time or two and then the starter just clicks. I replaced the battery just a few months ago and the starter is about 3 years old.

The last time I drove it, the turn signals didn't function and the speedometer stopped working and the automatic transmission down shifted very hard.

The truck has the 5.0 engine with automatic transmission and 4 wheel-drive and this is the first time I've had a problem like this. It has just over 150,000 miles.

Any ideas or suggestions would be very much appreciated.

 

You're missing or have a corroded ground somewhere.
I've been scouring over the wiring schematic (my '94) for the instrument cluster for a couple of weeks now and, if memory serves serves me correctly, there's a ground that ties the turn signals with the PSOM and a couple of other things together.........I just don't have my Haynes manual with me right now to tell you which ground and where it's located (seems to me it's the one behind the drivers side kick panel).
Perhaps someone will chime in here and give you the definate location of that ground.

Also, if the PSOM (speedometer) stopped working (due to a bad or poor ground), the transmission will go into "limp mode".
In "limp mode" you WILL experience VERY HARD shifting, believe it or not, "limp mode" (harsh shifting) is enabled to protect the transmission from destroying itself.

LATE EDIT: After reading this again, it sounds like the negative cable at the negative cable clamp (that clamps on the battery post) and the wire from the negative post on the battery that goes to the fender ground are the culprits here. I'd remove them, check for corrosion, "wire brush" 'em up, coat with your favorite corrosion inhibitor, re-install and see what happens.


Should be simple enough..........


Bob

 

I will also add to check/clean the ground wire at the engine block as well.

 

The cluster has nothing to do with this problem.
The computer has nothing to do with this problem.
When you say it "clicks" do you mean one click each time the key is turned or does it have a series of fast clicks?

Yes it could be you have a bad alternator (ford sometimes calls it a generator).

The turn signals quit working and the speedometer stopped working and the automatic transmission down shifted very hard because of low voltage.
You should also have had the Charging System lamp on the cluster to come on and your volt meter should have read low.
Did you happen to put a tachometer cluster out of a 1992 or 1993 truck in it to get a tachometer?
This will cause this also.

Either the battery is not charged (series of fast clicks) or you have bad wiring and grounds (one click each time the key is turned).



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Each time I turn the key, there are a series of fast clicks. I suspected that the generator might be at fault. But, the dead speedometer and turn signals seemed pretty strange to me.

I'll replace the generator and see where we go from there. Maybe there's still a wiring or grounding issue as well.

I'll keep you informed.

Thanks.

 

Try this before buying another alternator:

"LATE EDIT: After reading this again, it sounds like the negative cable at the negative cable clamp (that clamps on the battery post) and the wire from the negative post on the battery that goes to the fender ground are the culprits here. I'd remove them, check for corrosion, "wire brush" 'em up, coat with your favorite corrosion inhibitor, re-install and see what happens."

Bob

 

The charging system:


/

 

Today, I cleaned the negative post on the battery, cleaned off all corrosion and cleaned and re-attached the ground. The cable doesn't show any signs of corrosion.

I attached the jumper cables for the first time since all of this happened and after a few minutes, the truck started up. Everything seemed to be working, signal lights, odometer, etc. But, the engine died and wouldn't re-start. The battery was dead. I'm sure I could get it started again using jumper cables, but I'm wondering if the generator isn't producing any power to re-charge the battery.

Would replacing the generator at this point make sense?

Thanks

 

You need to have the battery charged.
Then start the engine and with a voltmeter on the battery see what voltage the charging system is putting out.
The charging system is not design to charge the battery, only maintain the charge in the battery.
If you try to charge a dead battery with the charging system you will burn up the generating device.

Do not remove a battery cable with the engine running to try and test the charging system. This can and will send a 100 volt spike into the trucks electrical system and can destroy electrical devices such as the PCM, Radio and so on.

 

After charging the battery, the truck runs fine for a while and then the problems re-occur and the battery is dead. My guess is that either the battery is bad (it's still under warranty) or there is a short somewhere.

Does that sound about right? How difficult is it to track down an electrical problem?

Thanks again for your help!

 

After charging the battery you needed to put a voltmeter on the battery and start the engine to see if the charging system was working or not.

 

Check your fuses - there's one in the fuse panel by the steering column that does the transmission. If it's blown or the filament is partially blown, your truck will do a bunch of weird things: hard shifts, loses the speedometer, etc. Replace the fuse, and if it blows again, there's a switch on top of your engine that controls all of those things and it needs to be replaced.