Test Plug Questions
 

Can anyone tell me what each of the, what i am assuming are, test plugs in the engine compartment of a 944 are used for? I have found a total of three, there is one on the driver side near the power brake booster, one mounted near the fender on the passenger side in front of the battery, and one coming from the wiring harness in the rear of the engine.

I have used the test plug on the driver side to disable the Idle Air Controller by jumpering two of the terminals, but what other functions does this and the other plugs serve?

Thanks in advance.

On passenger side infront of battery, i assume you mean right infront of the firewall. This is the cruise control connector (assuming your car does not have cruise).

On the rear of the engine i am guessing you mean the sensor on the hoist ring. That is the TDC sensor which was only used by the factory for diagnostic. It serves no actual purpose other than that. The other end is connected to the speed / reference sensor bracket and it can be removed if desired.

Im not sure what good the test port by the drivers strut tower is for the n/a cars other than disabling the ISV. For the turbo's a blink code tester can be hooked up to it (factory tool or you can make one). This will tell you the stored boost related error codes that the KLR stores while the car was running.

Thanks Techno Duck.

It is true that my car does not have cruise control and I had just realized this may have been what the plug was used for after I posted this question. Haha! As for the sensor on the rear of the engine, it appears to be a long round connector with a small cap in the end. However, mine is in a bracket that looks like it was once mounted somewhere on the car but is now just laying behind the engine. I'm assuming this is the same as the sensor plug you mentioned.

Thanks again!

Yup, sounds like the same connector. If you take the plug off the top it is a 3 pin connector.

O2 sensor connection, if three prong plug inside??

The other, near the brake booster is used for adjusting/testing the Carbon Dioxide levels emitted.

My best guess