Hey guys,

Now that I got my 94 7.3 IDI running with your help, I need to fix a bunch of little things.

I really need a service manual, but for now, can you tell me (or better yet show me with pictures) where the following sensors are:

1. Coolant
2. Oil Pressure
3. Tachometer

None of these gauges work. I don't know if it is one big problem (is that possible?) with the gauges or just worn out sensors. I'm guessing the latter due to the fact that nothing else was maintained on this truck by the previous owner.

I've already replaced all the fuses as the previous owner had put in whatever fuses he had laying around without regard to amperage.

Thanks,

Jason

 

 

The tach sensor is on the top of the IP timing gear housing right next to the oil fill.

The oil pressure sensor is on the top back of the engine right behind the intake manifold
There are two coolant sensors, one for the over temp light and one for the gauge. They will be on the drivers side front of the engine, the larger one that is closest to the head is for the over temp light. the smaller one that is closer to the IP gear cover is for the gauge. (Edit: the above diagram has the positions reversed however i just checked and my 6.9 is as I described)

Hope this helps

Bill

 

Oil pressure is on the back of the block behind the GP controller.
Tach sensor is the two wire nut lookin thing in front of the IP in the gear cover.
The gauge temp sender is in the front of the block on the right side just below where the intake meets the head on #2 cylinder.
The light temp sender is in the left cyl. head towards the front.

 

Awesome info guys. Thanks! I'll go through these this week and let you know what happens.

 

Before replacing all of the above I would pull the dash cluster out of the truck and clean all of the connections. It could be the plug on the back of the cluster has a corroded power connection, this would cause all of the gauges to be dead as they are all supplied power through the same source. All of the sensors are on the ground side of the circuit.
Clean the connections with a brass brush (disconnect batteries first) and this may take care of your problem.

 

I was just about to ask this. I replaced the $7 oil pressure sender to test as this was the cheapest one. The oil pressure gauge still didn't work, so I pulled the dash cluster. The only gauges that currently work are the speedometer, alternator, and odometer (which is digital). The plugs look clean, but the copper connections on circuit plastic are pretty dirty and a little bit sticky. I'm going to clean them both. Thanks!

 

Well, cleaning the connectors and the copper on the PCB where the connectors plug in did not help anything. On closer inspection, the PCB appears to be pretty corroded. I think that's the problem as the only gauge "wired" to the PCB that works is the alternator gauge and that is the only non corroded part of the PCB circuitry.



Any suggestions? Replace the PCB? Send to instrument cluster shop?

 

Fixed!

I took the PCB board off the back of the cluster, peeled apart the two layers so I could access the copper circuits (as the the two layer are separate circuits), soaked it in CLR for a few hours, then used a tooth brush to brush off the corrosion, soaked for 30 more minutes, brushed more, and repeated this several times until I got all the corrosion off I could w/o damaging the copper.

BTW, I also submerged the 2 resistors as I couldn't soak it properly w/o doing this. I wondered if it would ruin the resistors, but took the chance, as I would have the replace the PCB or the cluster if this didn't work anyway. I thoroughly sprayed the PCB with electrical cleaner after the last scrubbing and let it dry overnight before reinstalling.


I reinstalled the PCB and the cluster. The temp gauge and oil pressure gauges now work. The tack gauge give a reading but doesn't move (so I think that's the sensor).

Picture of soaking (weight down by screwdrivers because I didn't have much CLR on hand:



PCB after scrubbing

 

Glad to hear that it worked for you!! The tach sensors are notorious for going bad but you may try removing it and cleaning any iron filings that may have accumulated on the bottom of it. Often that will restore the sensor to working condition.

 

I'll pull the tach sensor and try that. I think I'm going to skip the tach for now, as I don't really need it, and try to get the other critical items done to make it road worthy, namely get the wipers to work so it will pass inspection, and replace the power steering hose, which came to me wrapped in duct tape. I have several other non critical items, like getting the fuel gauge to work (the wiring for the dual tanks/switch/block was butchered by the previous owner), but I'm close to getting this thing on the road

I'll search for existing threads on the wiper motor and create a thread if I need one. The wiper switch appears to work as I'm getting 12 volts to the power wire at the motor terminal when the switch is on.

 

Is the tach/rpm sensor called something else and/or is it hard to find? OReillys didn't have a listing for it, Rockauto.com doesn't have a listing for it. Strange

 

tach sensor.motorcraft E5TZ-17B384-A


http://www.ebay.com/itm/E5TZ17B384A-Ford-Sensor-Assy-/350986084015?pt=Motors_Car_Truck_Parts_Accessories&hash=item51b8669eaf&vxp=mtr


E5TZ-17B384-A - Ford SENSOR ASY

 

thanks. I cleaned it to no avail. Will order new one when other critical items are repaired

 

you can test it.i sure would as it's not chump change (and did.i just cheated,and used the good one from the other truck to see if it would cure what ailed her and it did) you'll have to search as i don't recall the info of what the wires to the plug should be nor the resistance reading between the two wires of the sensor.i want to say it's like 2-3k ohms......but don't trust that.