Identifying Wires in my Engine Compartment - Oil Pressure & Water Temp.

[Bronco638]

My 1980 F-150 now has the 'new' drivetrain installed; 302 w/SROD. The truck had the 351M/C6 from the factory.

I am trying to figure out what wiring remains from when the original drivetrain was removed. Specifically, I'm trying to find the wires for the water temperature sending unit (red w/white stripe) and the oil pressure sending unit (white w/red stripe).

Here's what on the driver's side wheel well in the engine compartment:



The connection in the yellow box is what I'm trying to figure out. There's three wires there. I'm pretty sure two of them are the ones for which I'm searching: water - R/W and oil - W/R. What I'd like to know is what the other wire is (and maybe what connector that is). The third wire appears to be red with green or brown stripe but it's very hard to tell.

I've been looking in the EVTM and thought that the connector might be C325 but the EVTM says that connector is round with eight wires (unless it means eight wires total? And, the EVTM gives varying locations for that connector). What's even more odd is that all of the wires, going INTO the male connector, have different color codes from the wires LEAVING the female connector.

The two wire connector, in the red box, is for the DuraSpark module I believe.

Can anyone verify that those are the two wires (temp sender & pressure sender) for which I'm looking? Any chance anyone can ID the third wire?

TIA

[viven44]

Ford changed the coloring over the years.. Purple/Pink, etc etc... 1980 was also the one year wonder in wiring. I have the EVTM as well and it does say 8 terminals!! Has to be a mistake..

The most fool proof way is to disconnect the connector and just confirm with probes and a multimeter....
(Measure resistance between the sending unit wire and the guessed wire, etc). I always insert a paper clip in the terminals and then clip a probe to that.

The green wire should be for tachometer, should go to ignition coil negative.

The one in the red box does appear to be the DS-II. White wire should receive battery voltage while ignition is in Run and Red wire should receive battery voltage while cranking (you can also test this with probes/multimeter).... this gets swapped at the module if you had the module (Red becomes white and white becomes red!!)

[Bronco638]

viven44 wrote

Ford changed the coloring over the years.. Purple/Pink, etc etc... 1980 was
also the one year wonder in wiring.

I had forgotten about that. A wiring diagram, while hard to read, may be the key here.

viven44 wrote

 I have the EVTM as well and it does say
8 terminals!! Has to be a mistake..

That connector has four wires on one side (the side with the green wire) and three on the other (visible in the image posted). Also, the three wires that go out of frame have cut ends. There's no terminals that would provide a clue as to what they were attached to. You'd expect to see the 90* push on connectors for those two sending units.

viven44 wrote

The most fool proof way is to disconnect the connector and just confirm with
probes and a multimeter....
(Measure resistance between the sending unit wire and the guessed wire,
etc). I always insert a paper clip in the terminals and then clip a probe to
that.

The issue is that neither the temp. sending unit nor the pressure sending unit has any wires currently connected to them.

viven44 wrote

The green wire should be for tachometer, should go to ignition coil
negative.

The green wire doesn't come out of that connector, it only goes into it. I do have the coil "horseshoe" and the part of the DuraSpark harness that goes from the module to the distributor. I believe the tach wire is part of that harness.

I forgot to mention that the 302 has an HEI distributor. I don't think the 351M did (it used the DS module).

viven44 wrote

The one in the red box does appear to be the DS-II. White wire should
receive battery voltage while ignition is in Run and Red wire should receive
battery voltage while cranking (you can also test this with
probes/multimeter).

Could I use these wires and connect them to the HEI BAT lug as the power source for the distributor?

viven44 wrote

... this gets swapped at the module if you had the module
(Red becomes white and white becomes red!!)

That I recall from my old '85 Ranger with the DS II. Geez Ford.....

[viven44]

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[viven44]

I have the 1980 EVTM. The only references to C325 are as follows... I am seeing a green wire in your pic so I'm not sure

R/LB coming in from ignition run --C325-- R/LB going out to ignition coil +

R/YH coming in from Fuse 2 via S404 --C325-- R/YH going out to Anti-diesel Throttle solenoid positioner

If you have gauges

R/W coming in from water temp sending unit --C325-- R/W going to water temp gauge via C208
W/R coming in from oil pressure sending unit --C325-- W/R going to oil pressure gauge via C208

If you have warning light
W/R coming in from oil pressure switch -- C325 -- W/R going to onto oil pressure warning indicator light via C208

[Bronco638]

viven44 wrote

I have the 1980 EVTM. The only references to C325 are as follows... I am
seeing a green wire in your pic so I'm not sure

R/LB coming in from ignition run --C325-- R/LB going out to ignition coil +

R/YH coming in from Fuse 2 via S404 --C325-- R/YH going out to Anti-diesel
Throttle solenoid positioner

If you have gauges (I do)

R/W coming in from water temp sending unit --C325-- R/W going to water temp
gauge via C208
W/R coming in from oil pressure sending unit --C325-- W/R going to oil
pressure gauge via C208

I found the exact same thing. What's difficult is that the four wire colors that come into the connector in the image are not identifiable. I can't tell if they're red, orange or pink (aside from the green and white wires). Those four also seem to be of different gauges. The green wire appears to be 12 or 14 gauge while the other three are 16 or 18 gauge.

I went out to the garage and took a closer look. Those four wires appear to be (in no particular order); green, white, red/white stripe and orange (maybe with yellow hashes?).

On the opposite side of that connection, the white wire corresponds to white/red, the red/white corresponds with red/white and green corresponds with red/??? stripe. The orange wire has no corresponding wire on the other side of the connection.

At this point, I think I've found the water temperature sender (R/W) and oil pressure sender (W/R) wires. The color coding seems to be the same for F Series as well as 80s Rangers. I am curious as to what the third wire color code and function is.

[viven44]

The only thing I can suggest is to use a in-line 1 amp or 0.5 amp fuse and connect those wires being guessed as for sending units to ground... if the gauges move to max then you have found the answer..

The mystery of that 3rd wire is to be determined still...

[Bronco638]

viven44 wrote

The only thing I can suggest is to use a in-line 1 amp or 0.5 amp fuse and
connect those wires being guessed as for sending units to ground... if the
gauges move to max then you have found the answer..

This is assuming that there's a power source (battery) in the truck, right? As of now, there isn't one.

viven44 wrote

The mystery of that 3rd wire is to be determined still...

Yeah...