I have a 1990 F-150 with a 5.0 litre EFI. Recently, in tearing down the engine to replace the head gaskets, I unwired the Throttle Position Sensor (TPS) but failed to mark the wires. From the TPS are an orange wire, a black wire, and a green wire. The wires were connected (twisted together and taped with electrical tape) to a white wire with a white tracer, a white wire with a red tracer, and a black wire with a white tracer; but since I did not mark the wires before disconnecting them, I do not know how to put them back. I know next to nothing about auto electronics, but I do know that wiring the TPS incorrectly will fry the electronics. I have left the TPS unwired until I can find someone or some literature to tell me how to correctly reconnect it.

Can someone please tell me how to correctly rewire the TPS?


Thanks a bunch.

 

I'm a little confused as to what you did. The TPS should just unplug from the main harness with no need to cut or take any wires out of the connector. Orange is a 5V reference voltage wire; Green is variable - the output to the computer; black is signal return wire.

 

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I own a 1990 5.0 and it mirrors your description. I have had the throttle body assy off on several occasions for maint.
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Additionally, (Indiancars) the TPS segment connects to cannon plug roughly 6'' upstream ( on a bracket mounted to the throttle body), thus no need to ever cut the wires to facilitate removal. Maybe replacing the TPS segment is a better choice than splicing or what not?

 

Quote:

Originally Posted by EPNCSU2006

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To both of you, thank you for responding.

I did not cut the wires. I bought the truck from a former co-worker a few years ago. Apparently he had done some work on the vehicle that I did not know about. The connector was missing and the wires spliced together when I bought it. This is the first work I have had to do on the truck other than routine maintenance, oil changes, etc., since I have owned it. Before now I had not really noticed that the connector had been removed and the wires spliced. I have no idea why he would have done this. Apparently he had his reasons. Anyway, what is done is done.

Replacing the connectors would be fine except for one thing: I will have to buy the entire wiring harness, because the wires that connect to the TPS are part of the fuel injector harness. If I can find the connector without having to buy the entire harness, then I will do so. Still, it will require splicing, and I really need to get the TPS wired in as soon as possible. Also, the TPS is working fine, so why go to the expense of both a new wiring harness and a new TPS when it is really unnecessary?

I appreciate your advice about not cutting wires, but I already know that. It was a pre-existing condition. It was stupid of me to fail to mark the wires before disconnecting them, but it happened. If the connector had been there, I would have simply unplugged it. Then I would not have had to bother this forum with my problem.

Thanks again for the advice about not cutting off connectors, but I know no more now than I did when I posted the original problem and question. Do either of you know which wire on the TPS goes to which wire on the harness?

To repeat the choices:
TPS: Orange, Green, and Black
Wiring Harness: Grey w/White tracer, Grey w/Red tracer, and Black w/White tracer.

Oh. Indiancars is my username, but you can call me "Al." That's my name.

 

The wire colors on the harness have also been changed. They are supposed to be the same as the TPS pigtail. What I would do is test continuity on the wires - the Orange wire on the EVP sensor is connected to the orange wire on the TPS - so test for continuity between the orange wire on the EVP and one of the three white wires you have. Then the black wire on the EVP also connects to the black wire on the TPS - check continuity between the black on the EVP and one of your unknown white wires until you have a match. Then the third wire will hook up to the green wire on the TPS.

 

Thanks, EPNCSU2006.

Actually, I told you wrong. The wires I was calling "white" are actually grey: grey w/white tracer and grey w/red tracer. Still, your information will help me get it right.

That's the trouble, sometimes, with buying someone else's vehicle and not knowing all the mechanical history of the vehicle. Things get changed, and the next owner has to figure out what was changed and how to work around it.

Thanks for your patience.

Al

 

Only try'n to help Al, I'll check back later to see how its going, seems the other fellow has given a good description on how to mate up the wires.
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Keep on Truck'n

 

Gnatzter

Thank you for your good advice. You did help, and I appreciat that. I have a day off tomorrow, so I will get the truck squared away then. I will let you know how it works out.

Thanks to you and to EPNCSU2006 for your help.

Al (Indiancars)

 

EPNCSU2006 and Gnatzter


Many thanks, EPNCSU2006, for your information. It helped me figure it out very quickly. Here are the results:

The EVP is of the light grey variety (as opposed to black). The EVP connector has the grey wire with the red tracer and the black wire with the white tracer that were originally connected to the TPS. The third wire from the EVP is a black wire with a green tracer. Since the EVP black wire with the white tracer is the only one of the black wires originally connected to the EVP, it makes sense that it is connected to the black wire on the TPS. Following the same logic, since there is no orange wire going to the EVP, the orange wire connects to the grey wire with the red tracer. That leaves only the grey wire with the white tracer on the harness side and the green wire on the TPS pigtail. That is how I connected the wires, and it worked.

So, the correct combination is: Black TPS - black/white EVP; Orange TPS - grey/red EVP; and Green TPS - grey/white (assuming this is the output to the computer).

Thank you, EPNCSU2006, for the help. As I said, I know next to nothing about automotive electronics aside from basic electrical systems.

Thank you, Gnatzter, for your help.

Thanks to the Ford Trucks Enthusiasts forum for creating the means by which we were able to connect.

Al (Indiancars)

 

Glad it all worked out for ya AL, I hope my A/C vacuum leak problem works out this good....... still plugging away in a thread in here
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cheers

 

I hope it does, too. If I knew anything about A/C systems, I would be happy to help; but I know even less about A/C than I do about automotive electronics. I will keep my fingers crossed for you.

As they say in show business, "Break a leg."

Al