91 Ranger Engine Wire harness Question

[ranger85]

I have a 1991 Ranger 2.3 5-speed manual 2wd. I bought this truck used and I have slowly found out some interesting things about this truck. First is that the engine has been replaced with a 2.3 from a 1992 model. I found this out because the timing belt on a 91 has square teeth and the 92 has round teeth on the timing belt. The main issue that I am having is with the engine wiring harness. The wire harness in my truck doesn't have the wiring connectors for the coolant temp. sensor, and the intake air temp. sensor. Today I removed the wire harness from the truck to go through it with the help of wiring diagrams. I am curious if anyone has come across the same issue with there Ranger. Any information would be helpful.

 

[Mark_88]

I can't say specifically about what you are seeing but I can speculate. In some cases vehicles were produced halfway through a production year when the parts were used from a new product when they ran out of parts for the original design. Since they were compatible in many ways there simply was a shortage and they filled it with new product.

That might explain the timing belt...

However, if there was a swap, the previous owner may actually have swapped the engine and ran into problems before being able to figure them out and sold the vehicle half finished.

Not uncommon with DIY mechanics who are not aware of subtle changes from one year to the next so you may be right...

The wiring harness in the vehicle may not need those sensors to run if the computer doesn't know what the signal is for anyways. So the thing to do is either run the setup with the old wiring harness using only the sensors for that year or find a complete harness and computer that used the newer style.

There is likely someone on here that knows the subtle differences and can give you a more definitive solution or you can find the wiring diagrams from both the 91 and 92 2.3 engines and compare them.

There is a link to wiring diagrams in the Tech Articles section near the top of the website and someone recently posted one for consideration to be added to the collection already on site...

http://www.therangerstation.com/forums/showthread.php?t=174019

 

[tomw]

Both 1991 and 1992 model years should have had the EEC-IV OBD-I control system. Both should have air and coolant temp sensors. They should have EFI rather than a carburetor, and O2 sensor and a catalytic converter. If they don't have that equipment, they have been modified by a previous owner.
I don't know specifics on manifolds and ignition systems, but they all want coolant and incoming air temperature information.
tom

 

[scotts90ranger]

Around '91 was when they went from speed density fueling to using a Mass airflow sensor, so the intake temp sensor is in the MAF on the newer ones. I'm with Tom on the coolant temp though, they all have those, the wires should be there but the sensor could have moved a little, they're usually by injector 2...