Skip to main content ↑ ↓
Topic: 1980 Thunderbird Oil Pressure Sender- 3 wire? (Read 2519 times) previous topic - next topic

1980 Thunderbird Oil Pressure Sender- 3 wire?

Anybody know why the 1980 tbird would have a 3-wire oil pressure sensor? I have never seen an older ford with anything other than the single-wire sensors.

I ask because I am adding an aftermarket gauge, and I suppose I should figure out if it has a low-pressure shutdown or something that I will have to bypass if I disconnect the factory sender.

Anybody got a 1980 schematic?
CoogarXR : 1985 Cougar XR-7

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #1 –
Pm
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #2 –
PM me and i will tel you why!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #3 –
post it tom~!  :)


i am speculating its a simple variable resistor design,, our cars use a presure disc , either its open or closed.

I would like to have an intellegent oil presure system reading,, my 20th has this by use of the qty of bars shown on my full digital display,, however,, i do still have a single wire sendor and i have no clue how the car knows to display how many bars.
on the standard and buttstuffog clusters the single wire gizmo just supplies a light for low oil

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #4 –
the digital dash isn't even really an oil gauge. if you ground out the sensor it reads full pressure, disconnect it and it reads nothing. I think it would be easy to find a sensor that does more then an on/off switch when pressure is applied.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #5 –
Quote from: Haystack;426440
the digital dash isn't even really an oil gauge. if you ground out the sensor it reads full pressure, disconnect it and it reads nothing. I think it would be easy to find a sensor that does more then an on/off switch when pressure is applied.

With a buttstuffogue gauge, the oil pressure senders before '89/'90 are the large bell type that vary resistance with pressure changes... AFAIK the early digitalis use a light type sender with a resistor in line so pressure reads approx 2/3 scale or not at all... If pressure is varying with engine speed and temp, it no doubt is using a variable resistance sender...   

By '90 Ford Ford switched to idiot gauge operation to satisfy the OCD types that complained of low oil pressure at idle... For at least a few years the pre '89 senders can be used to convert the idiot gauge into one with real function, but by the early '90s the gauge was designed to operate only from a on/off sender... 

Three contact oil pressure switches include a double contact sender that generally kill fuel pressure or ignition if oil pressure fails... Was somewhat short lived feature as it cost extra to implement and total loss of oil pressure was a rarity anyway...

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #6 –
yeah. on ky first 86, it was only reading 10-12 PsI warmed up and the digi gauge beeped constantly once it warmed. it always read normal when it worked. I'm pretty sure that the car having 297k on it was low oil pressure.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #7 –
Quote from: TOM Renzo;426403
PM me and i will tel you why!!

I don't come here too often anymore.  I do have to ask something.
Why; in one of the few long-standing online communities for a vehicles with an admittedly smaller following; would we not share this kind of info?
Your reason is yours and if you feel you don't owe anyone an explanation, that's well and good.  I do think it might possibly benefit if you just posted the answer to his question here though.

Meh.  Maybe I'm looking too deeply into things... I would be curious myself to know why.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #8 –
Quote from: TurboCoupe50;426448
With a buttstuffogue gauge, the oil pressure senders before '89/'90 are the large bell type that vary resistance with pressure changes... AFAIK the early digitalis use a light type sender with a resistor in line so pressure reads approx 2/3 scale or not at all... If pressure is varying with engine speed and temp, it no doubt is using a variable resistance sender...   

By '90 Ford Ford switched to idiot gauge operation to satisfy the OCD types that complained of low oil pressure at idle... For at least a few years the pre '89 senders can be used to convert the idiot gauge into one with real function, but by the early '90s the gauge was designed to operate only from a on/off sender... 

Three contact oil pressure switches include a double contact sender that generally kill fuel pressure or ignition if oil pressure fails... Was somewhat short lived feature as it cost extra to implement and total loss of oil pressure was a rarity anyway...

Never understood the point of that inline resistor.  System works fine without it.  I've been running the larger unit without a resistor for a few years now without issue.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #9 –
Quote from: V8Demon;426483
Never understood the point of that inline resistor.  System works fine without it.  I've been running the larger unit without a resistor for a few years now without issue.


Assuming the resistance of the variable sender matches the requirement of the gauge, a separate resistor should not be needed... This would be true in case of buttstuffog or digital clusters...

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #10 –
I had the resistor in place when I got the car which was in line with the smaller style unit.  I remember seeing those resistors all over Mark VII's in a yard that had a ton of them up here many years ago.  IIRC this is where I first saw the larger style unit.  I'm pretty sure that there were a couple of cars that had the resistor and the large style sender....

I think it was you Tom who mentioned that resistor was a 22 OHM unit.  I have a thread on here somewhere about it.....
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #11 –
Quote from: V8Demon;426482
I don't come here too often anymore.  I do have to ask something.
Why; in one of the few long-standing online communities for a vehicles with an admittedly smaller following; would we not share this kind of info?
Your reason is yours and if you feel you don't owe anyone an explanation, that's well and good.  I do think it might possibly benefit if you just posted the answer to his question here though.

Meh.  Maybe I'm looking too deeply into things... I would be curious myself to know why.

In that particular  car the extra lugs are used to cut through 12 volts to the choke thermostat!! It has a carb the third lug is a standard point to operate the gauge, Some cars used these switched to kill the electric fuel pump when the engine is not making oil pressure.
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #12 –
Thanks Tom. 
That's actually quite interesting and a good safety feature. 
Too bad it would have killed mine many times in the past when I was making 20 pounds of pressure.  I should just replace all that wiring and see what happens.  Perhaps It's beat up underneath the sheathing.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #13 –
Yeah, I dug up one of my old ford books and Tom is right. One lug is for the oil light, one for the electric choke, and one for 12+ (looks to be a switched hot coming from the ignition switch). So if I eliminate the factory sender, should I just jumper the 12+ to the choke terminal? I am not too familiar with carbs. If it's a switched hot, it will only get 12+ when the key is turned (the engine could presumably not be running though). Anybody see a problem with that? Maybe I don't understand why it's a safety feature...
CoogarXR : 1985 Cougar XR-7

1980 Thunderbird Oil Pressure Sender- 3 wire?

Reply #14 –
I used to do it that way all the time. BUT!!! Do not key the car and not start it. Reason being the choke will come off and a no start when cold.
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!