So far nobody has an explanation for this one.
The "check engine" light on my 91 Ranger came on some time back. The truck did not run any different after the light came on than it did before the light.
The self-test just gives Code 22 on KOEO (both O & C codes). Every reference that I have found says this is "MAP/BP sensor out of range". But Ford says the 1991 Ranger XLT 3.0L v6 does NOT even HAVE a MAP sensor.
Yes, I know that it has an MAF sensor instead thought nobody has been able to explain how a Mass AIR FLOW system can replace a Manifold absolute PRESSURE (ie vacuum) based system.
So what is causing the computer to read the code 22? And what can be done to correct the problem & turn the "check engine" light off again.
And, BTW, yes I have reset the soft code storage. And know that the reset worked because immediately after having done the reset the KOEO test gave 22 22 1 11 indicating that the C (soft code) storage had been cleared.
On the same topic, can anyone tell me for certain where the microprocessor unit that generates the self-test codes is located on the truck? I have 3 different answers so far but none appear correct.
While we're at it, how exactly does an MCU differ from a PCM or an EEC or an ECU. Are they all the same unit or different physical modules?
TIA!
Bob W Miami FL