Electrical Temperature Sending Unit Problem - Help

Vic1978 · Apr 18, 2018

I have a 1978 Cobra, 302/auto. I asked this question on my build thread with no luck.

I have a question about what I think is the temperature sending unit wire hook up. The one that I believe attaches to the sending unit is a connection with a red rubber protection piece. The connection has a two “prong” connection to the sending unit.

All of the sending units I have seen and the one I bought has a single prong connection.

How are you guys hooking this up to the original connector?

LILCBRA · Apr 18, 2018

I'd help if I could, but I haven't run the original temperature gauge in years!

Vic1978 · Apr 19, 2018

LILCBRA said:
I'd help if I could, but I haven't run the original temperature gauge in years!

Thank you for the reply. I’d like to get all of the stock gauges working properly and there is 0 information on this.

jozsefsz · Apr 20, 2018

Well... I don't have the 302 (have a 2.8) but have been working on Fords with 289's and 302's (from the 60's through 90's) and have never come across the red connector you picture. Coolant temperature sending units I've seen were always one-wire with a simple push-on connector, until EEC-IV where a 2-wire connector is used for the computer ECT feed (even through the 90's the gauge still operates on a separate one-wire temperature sender).

I'm not sure what that guy is - perhaps used for an aftermarket gauge or some piece of emissions equipment I've never seen (a '78 has a VV carb I think which has some wiring - I've never seen one of those in real life either as they usually end up in the trash). If it is for the gauge, you could try to short the pins together, or to ground, and see if your gauge moves. If it's not for the gauge, you might blow a fuse or something so I'd probe it for voltage first.

Vic1978 · Apr 20, 2018

jozsefsz said:
Well... I don't have the 302 (have a 2.8) but have been working on Fords with 289's and 302's (from the 60's through 90's) and have never come across the red connector you picture. Coolant temperature sending units I've seen were always one-wire with a simple push-on connector, until EEC-IV where a 2-wire connector is used for the computer ECT feed (even through the 90's the gauge still operates on a separate one-wire temperature sender).

I'm not sure what that guy is - perhaps used for an aftermarket gauge or some piece of emissions equipment I've never seen (a '78 has a VV carb I think which has some wiring - I've never seen one of those in real life either as they usually end up in the trash). If it is for the gauge, you could try to short the pins together, or to ground, and see if your gauge moves. If it's not for the gauge, you might blow a fuse or something so I'd probe it for voltage first.

Interesting, good info. I will see about tampering with the wire to see if I get a reaction from the gauge.

Thank you

COBRA 7 · May 8, 2018

Vic1978. Did you get it? I'm getting ready to rewire my dash and I can tell you what I find if you need. I have a 78.

Vic1978 · May 8, 2018

Nope, I haven’t been able to find what’s seems to be the correct temperature sending unit with the right connection. Can you send a picture of your temp sending unit that is on your intake? I want to see if your connector is the same as mine.

Can you also take a picture of the back of the gauge cluster (circuit board, speedometer, tach, tach adapter) with each of the part numbers please? A picture of the tach adapter connector with wire colors.

Thank you for your help.

COBRA 7 · May 11, 2018

Vic1978 . I can help you. It may be two weeks before I can get the info. you need. I have three cars I'm working on not including mine.
First - The wire connector in your first picture is for an oil sending unit. (A White wire?) Ground this wire and It turns on the dash light for no oil pressure. Looks like you have an oil pressure gauge setup with a small copper tube. Note: I put a tee fitting in mine and run a gauge and a oil light.
Second - I'll get a picture of the temp. sending unit on my intake with the connector. If memory serves me it is a female spade connector Red / White tracer.
Third - I'll get a picture of my cluster when I'm done rewiring it. My tach I think is from my 4-cyl. It is close to the correct RPM so I use it. Tach # D7ZF - 17360 printed CIRCUIT BOARD # D6ZF - 10C956 plastic DASH HOUSING # D4ZF - 10848 - AA NOTE : plastic DASH HOUSING is the part that the printed circuit board lays on. Sorry. No numbers for the speedo.
I have been going through the PDF I have included and the wire colors seem to be correct for my 78 MII.

Vic1978 · May 17, 2018

Anyone ever see one of these? I bought this temp sender off of Ebay for the same year LTD, TBird. I bought it because it looks like the same connection that would fit for this stock Ford connector and same year.

I’ll put it on this weekend to see if it works.

Vic1978 · May 17, 2018

COBRA 7 said:
Vic1978 . I can help you. It may be two weeks before I can get the info. you need. I have three cars I'm working on not including mine.
First - The wire connector in your first picture is for an oil sending unit. (A White wire?) Ground this wire and It turns on the dash light for no oil pressure. Looks like you have an oil pressure gauge setup with a small copper tube. Note: I put a tee fitting in mine and run a gauge and a oil light.
Second - I'll get a picture of the temp. sending unit on my intake with the connector. If memory serves me it is a female spade connector Red / White tracer.
Third - I'll get a picture of my cluster when I'm done rewiring it. My tach I think is from my 4-cyl. It is close to the correct RPM so I use it. Tach # D7ZF - 17360 printed CIRCUIT BOARD # D6ZF - 10C956 plastic DASH HOUSING # D4ZF - 10848 - AA NOTE : plastic DASH HOUSING is the part that the printed circuit board lays on. Sorry. No numbers for the speedo.
I have been going through the PDF I have included and the wire colors seem to be correct for my 78 MII.

Cobra 7 thank you for the reply and helpful information. I haven’t had a chance to work on the car but hopefully this coming weekend.

jozsefsz · May 19, 2018

That sending unit is wild Vic, I've never seen one like it. I can't find one listed anywhere for a 78 Ford that looks like it. And I used to own a '78 LTD that I had apart more than once and it was definitely 1-wire though mine had the 351M. . It looks to be a match though, I hope it works out for you. I'm still just a little boggled as to what the heck is going on. Your car wouldn't be some 'California' spec model perhaps?

Vic1978 · May 19, 2018

jozsefsz · May 19, 2018

I believe you for sure, perhaps part of the problem is that some folks have it listed as a door jamb switch. lol
http://rover.ebay.com/rover/1/711-5...0001&campid=5335821607&icep_item=232513151011

Looks like it cross-references to a Wells TU26 or Standard Motors TS22 should you ever need another one. None of the usual catalogs I check show it fitting a 78 Ford, but that doesn't mean much these days.

COBRA 7 · Jun 1, 2018

Here is the temp. sensor Bottom photo. ( Red with White tracer wire )and oil pressure Top Photo ( White with Red Tracer wire. ) The wiring for the dual lead temp. sensor. One wire goes to temp.light or gauge. The other wire goes to a Carb. Valve Control Solenoid. Must be for emissions.

Vic1978 · Jun 5, 2018

Here is my plug with the three wires. I’ll get a single plug to put on the red white/tracer wire and install a temp sending unit like yours. Hopefully it will work because installing the other did not work.

Thank you for your help COBRA 7.

Vic1978 · Jun 9, 2018

I got the temp gauge to work by installing a single connection sending unit and wiring it to the red wire with white tracer. However it runs at the half way mark on the gauge. Is that where these cars run normally?

I have a new water pump, new radiator, new sending unit, fan shroud and new hoses.

LILCBRA · Jun 9, 2018

Way back in the day when my car was still all stock, my temp gauge ran slightly shy of center, roughly one needle width less than what you show. I'd say you're probably good....

Vic1978 · Jun 24, 2018

LILCBRA said:
Way back in the day when my car was still all stock, my temp gauge ran slightly shy of center, roughly one needle width less than what you show. I'd say you're probably good....

I also installed another aftermarket temp gauge. So running stock and the aftermarket. Aftermarket says 190.

Thank you LILCBRA

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