PCM question

[DCMoose48]

On the PCM there is a hole about 2" in diameter that looks like some type of hose could be attached to it. Should something be attached there or is it just some sort of ventilation hole? After having the PCM replaced recently for the third time in less than 3 years my mechanic told me to go to a dealership and ask but they want to charge me for an appointment just to ask a question. I can't find anything about it in the Haynes book. Any help is appreciated.

1990 B250 5.2L 318 V8

[oopsth]

Originally Posted by DCMoose48

On the PCM there is a hole about 2" in diameter that looks like some type of hose could be attached to it. Should something be attached there or is it just some sort of ventilation hole? After having the PCM replaced recently for the third time in less than 3 years my mechanic told me to go to a dealership and ask but they want to charge me for an appointment just to ask a question. I can't find anything about it in the Haynes book. Any help is appreciated.

1990 B250 5.2L 318 V8

I have a 89 B250 and there is an air tube that Y's off the main air inlet and connects to the front hole of the PCM allowing for air flow over the PCM and exits to the right rear of the PCM. The main air inlet comes from just front of the radiator to the one intake of the air cleaner.

[rangerreb]

Yes, you need the pipe replaced or you will keep burning up the PCM.

[neon_rt]

I've seen where some people had modified their air inlet for more performance, bypassing the original ducting that cools the PCM and yes, you will burn them up one right after another if you do that. One solution is to get a 12v Computer cooling fan and mount it on the duct so it blows air directly onto the PCM. You will want to wire it so it will always run when the key is in the "run" position.