Ford F150 Tempeartuer Gauge won't work

1995 Ford F150 6 cylinder 4.9L

My temperature gauge on the dash has been stuck on COLD for about a year. The heater produces hot air no problem. I changed the thermostat anyway, but it didn't make any difference. So when my mechanic was doing some other work on the engine, I asked him to change the temperature sending unit and check the wires for damage while he had the truck on the lift.. He changed the temp sending unit and he said the wires looked OK visibly. However the needle still is stuck on COLD no matter how long I drive it. The engine runs fine, and there is no evidence of overheating. I would just like to get the temp gauge to work, so I can monitor things better on this old truck.

I am wondering if there is any electrical connection in the steering column (clockspring or ignition switch) that could be broken, and cause the temp gauge needle to malfunction. The reason that I say this, is because there seems to be a lot of "up and down" play in the steering wheel.

Any insight into what would be a likely cause?

Thanks,

Gary

Reply to
GWK
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The easiest test would be to locate the temp sender wire and ground it with the key on. Now look at the temp gauge -- if the wire and gauge are OK, the gauge will be pegged on "hot". If it still doesn't move off of "cold", then troubleshoot the wire from the sender to the instrument cluster harness. If that is OK, test the back side of the temp gauge -- be sure that one of its terminals has B+ with all connectors attached and key on.

The only things that excess steering column play could affect in this circuit would be pinching a wire in the column harness or rubbing a wire bare near the shift lever assembly or exposed section of steering shaft areas -- which would have to blow a fuse that is common to the temp gauge power supply. Usually other nearby gauges would suffer if this happened. The actual temp wire is nowhere near the pivot point of the steering column.

As an aside, If the pivot pins or housing is cracked in your tilt steering column mechanism, you should get that fixed post haste. It's an unsettling feeling to be driving down the road and have your steering wheel come apart. BTDT once during a test drive on a ratted out sedan. Not fun...

Toyota MDT in MO

Reply to
Comboverfish

More likely is that the gauge burnt out. Personally I would replace the temp and the oil pressure gauges with aftermarket anyway. The Temp gauge is actually a gauge BUT the oil pressure gauge isn't. It is a glorified idiot light. Ford put a resistor across the gauge so it reads a constant pressure. It is possible to convert it to a true gauge though, you replace the sender with a gauge sender and remove the resister.

Reply to
Steve W.

is this also true of a '93? Do you have more info. on how to do this? (i.e. use a Stewart Warner sender, or one from an earlier year Ford, or other...?)

thanks,

nate

Reply to
Nate Nagel

From what I have seen and read it covers years 1987 through at least

2000 and involves most of the domestic Ford vehicles both cars and trucks up to the F-350 and includes diesels. The "sending unit" is a switch that just makes the "gauge" pop up to a reading somewhere in the normal area on the dial as soon as the oil pump generates at least 3-5 pound of pressure. 97 and up started using a chip with the resistor in it to operate the gauge. The only way around that one is to replace the gauge with a true mechanical.

For a new sender these are parts that will work with the current wiring. Auto Tune: PT3077B Standard Motor Products: PS-60 Echlin: OP6091 Motorcraft: SW-1547-B, or E4ZZ-9278-A

You still need to find the 20 ohm resistor which can be in the sender, inline from the sender OR behind the gauge cluster or in the case of vehicles from late 96 through 2000 it is IN the chip on the cluster. The only way out on those later vehicles is to replace the gauge itself.

More info

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And from the f150 forum

The oil gauge on the Explorer isn't. Simply put, the indicator on the dash looks like a gauge, but it is really only a binary indication as to whether the pressure sensor believes that the engine has sufficient oil pressure or not. If it thinks there is sufficient pressure, then the gauge reads in the "Normal" zone, usually pointing to a single place (without varying based on temperature, RPMs, etc.). If there is not sufficient pressure, then the gauge reads "low." The first item below describes how to convert the "indicator" back into a gauge. Discussion on this topic follows:

I went ahead and installed the transducer today. It was a universal 1/4 pipe threaded sender with the "slip over threaded rod" style of electrical connection to the top. Plenty of room for the tee, original switch, and the new transducer. I removed the switch from the 45 degree long- shafted adapter. Used the end of the tee (not the center port) to the adapter, mounted the transducer upward and the switch outward (center port of tee). Was able to plug the original connector into the new transducer.

The gauge read just left of the N in Normal prior to disabling the 20 ohm resistor on the dash cluster. After shorting out the resistor, the gauge needle points to the A in Normal at 2000 rpm and around the O in Normal at a warm idle in gear. The needle is heavily dampened (so to react to changes) but is still a worthwhile modification.

I would say that the dash cluster removal is rather involved and not for the faint of heart. In fact, living without the resistor modification is really acceptable when you consider the gauge is dampened. If my wife would allow it, in retrospect, I'd have just done the tee and added the chime to the factory gauge but installed a real 270 degree mechanical gauge. And not touch the dash.

And now! What the manual says about the OIL PRESSURE GAUGE!

"When the engine oil pressure is normal, the oil pressure switch is closed (short circuit), allowing current flow through the 20-ohm resistor on the cluster flexible circuit into the gauge which drives the pointer to a position slightly above midscale. The switch opens (open circuit) when oil pressure drops to a critically low level (4.5 - 7.5 psi) causing movement of the pointer to or below the "L" band."

"NOTE: The pointer of the magnetic gauge will remain in it's last position when the ignition is turned off. It will move to the correct (or actual) indication whenever the ignition is turned back on."

Reply to
Steve W.

Cool, thanks. I'll probably be acquiring one as soon as I have time to take a day off and go to the DMV, and this is one of the first mods I'd want to do (I like gauges)

nate

Reply to
Nate Nagel

Thanks for advice. Is there an easy way to access the back side of the temp qauge on a 1995 F150 4.9L?

Gary

Reply to
GWK

Typically you remove the finish panel around the intrument cluster, then remove the screws holding the cluster in place. Now look at the back side of the cluster for screws or studs coming out directly behind the area of the temp gauge. *If* the gauge is mounted this way, then it is highly likely that those screws or studs serve double duty as electrical connections. If you don't see this arrangement, start carefully dismantling the cluster until you can locate the attaching screws for the gauge. Take pictures along the way, be neat and careful.

Toyota MDT in MO

Reply to
Comboverfish

I haven't been able to locate the temp sender wire or temp sender, although my mechanic did replace the temp sender. I was able to pull the instrument panel and find some temp gauge contacts directly behind where the temperature gauge is. They are labelled IGN, SIG, and GND. With the key turned to RUN, I get these voltage readings:

IGN to GND - 11.4 Volts SIG to GND - 5.0 Volts

Gary

Reply to
GWK

When I run a jumper from SIG to GND, the temp gauge needle jumps from COLD to HOT. So, I guess the temp gauge isn't broken. Maybe the wire from the temp sending unit to the temp gauge is bad.

Gary

Reply to
GWK

What is your definition of "SIG"? Is that what the cluster's printed circuit sheet has etched into it near one of the temp gauge terminals? --Or -- is it the harness connector right at the temp sender? If "SIG" is on the circuit sheet, then the gauge seems to react properly. You would need to test the wire after that result. If "SIG" means the latter, then the wire appears to work as well as the gauge does. Of course, this full grounding test just roughly passes both the gauge and wire; it is not a 100% guarantee that the wire and gauge are in total working order. It doesn't, for example, tell you that the gauge is capable of reporting various resistance loads correctly, nor does it tell you if the wiring is hanging on by just one strand.

Toyota MDT in MO

Reply to
Comboverfish

"SIG" is what is etched into the circuit sheet next to one of the temp gauge terminals. There are no visible wires on any of the 3 terminals, so I assume the circuit sheet connects to them internally. Temp Gauge stays pegged on COLD under all running conditions, regardless of coolant temp. I try to find temp sender wire and check that first.

Thanks,

Gary

Reply to
GWK

Just wanted to say thank you again; I bought the truck last night and am going to try to do this mod at the first opportunity.

nate

Reply to
N8N

My mechanic checked it out. The wire from the temp sender unit had deteriorated. He replaced it, and now the gauge works. Thanks,

Gary

Reply to
GWK

I have the same problem with my 2000 ford f150 5.4 L v8

Reply to
maweiss81

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