I'm putting an '89 engine {from a convertable with manual tranny} in my '91 {coupe with automatic tranny}. The water pump on my bad engine had two sensors on the back, one square green plug and one black round plug. My 'new' engine does not have the round black plug and sensor. Can someone tell me what that is for and how bad will it be not hooked up any more? Please tell me before I ruin my rebuilt 89 engine. Thanks.

 

Darn, no one wants to answer. How about.....swapping the water pump? I don't have a 91 manual so I can't say what it is. I sense that the broke engine is gone. TO THE TOP, BUMP...

 

I can tell you this. The square green plug is the ECU sensor. As long as both engines have this, you are OK. The other sensor is, I believe, not a sensor at all, but a switch (Check it on the old engine, it should read wide open). What the switch did was start the small fan in front of the radiator. It also lit a cooling fan warning light on your warning/clock console. If your car doesn't have this fan, don't worry about it. If it does, and you want it to work, you will need to add the switch to the water pump somehow, or get a universal radiator temp switch and install it in your radiator. Hope this helps.

Irv, Keith's dad

 

I belive the 2nd one is for the 3000rpm warm up... as they don't have them on the rad on the 89-91.