Bought a used 99 Ranger 3.0 with stick shift. Water temp and oil pressure are not reading anything until motor warms up a bit. Drive 1 mile or so and the gauges go "ping" and the oil pressure goes to middle and temp gauge reads cool, but not pegged below C like it was. Any ideas where to start ?

 

First off, the oil pressure gauge is a 'dummy gauge'. Ford originally had an actual oil pressure gauge, but people kept bringing their trucks in complaining of low oil pressure when it was just fine. So now the oil pressure gauge flies to the center as long as there's at least six (yes, SIX PSI) minimum of oil pressure. There's ways to get around this, but that's beyond what I'm talking about.

On the other hand, the coolant temp gauge is more truthful. I believe there are two water temp sensors for the Ranger, right near the water pump. One is for the ECU and one is for the gauge on the dash. I don't know which is which, but with the vehicle warm, disconnect one of the two. If the gauge drops or spikes one way or the other but then returns normal when said sensor is plugged back in, you've found your diamond.

It's possible the cluster has gone bad, it's possible that the sensors are going bad, and it's also possible that the wiring itself could be damaged. If I were to replace anything, though, it would start with both the water temp sensor (for gauge) and the oil pressure sensor for the gauge as well. I don't *think* they're too expensive, but I've never priced 'em.

One thing you could try before replacing them though, is whipping out some contact cleaner and giving both the sensor and it's connections a good soaking with that. WD40 makes a contact cleaner that's pretty good. It can be found in music shops, electronics stores, hardware stores, heck even Walmart has it. It could be just dirt in the connectors.

It's a rare, rare, rare occasion that the cluster itself is the culprit.

 

The water temp sender is the one with the single wire coming out of it, it makes its "ground" connection on the body where the threads come in contact with the steel.
Sometimes this area can become corroded and needs cleaning.

 

Both oil and temp gauges use engine as Ground, so that is the most likely place to start.

Make sure battery's Ground cable(s) are making good contact.
On the back of the drivers side head(V6 engine) there will be a Ground strap that runs from the head to the firewall, as Jeff R 1 pointed out.

Loosen strap and retighten at both ends, this is the main ground for all the cab electrics, when truck is assembled at the factory all the body parts are already painted, so none of the bolts holding parts together are very good Grounds, because they are not touching bare metal.

There are 4 main grounds on any vehicle
Battery to engine for starter motor and alternator, biggest cable because these are the biggest AMP requirements
Battery to Radiator support and inner fender for head lights and relays
Engine to Cab for cab electrics
Engine to Frame for tail lights, engine and trans are isolated from frame and body by rubber mounts.

If you can't find these it doesn't hurt anything to add another ground, just to be sure
And bare metal is needed, paint does not conduct electricity, but you can paint over it after installation to protect the bare metal

 

Thanks ArticWolk1911.

 

Thanks RonD. I will keep looking into it.

 

Thanks Jeff

 

Thanks for all the tips and suggestions - a new oil sensor in back of engine and cleaning up the ground connections has it all working like it should. Whew . . .

 

Good to hear !