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I need a ECU pinout for an 89 non-SE. The rad fans turn on when I connect the jumper to perform a check engine light blink code readout. There are no codes present the light functions normally and is currently off after resolving code 26.

 

This appears to indicate the 'switch' in the ECU is functioning normally along with both relays and all associated wiring. Might this indicat a faulty coolant temp sensor? (mine appers to be on top of the intake manifold w/ a yellow/brown and black wire)

 

The reason I need a ECU pinout: A black (GND) wire is disconnected / pulled out of one of the three ECU connectors. it has a pin attached that appears to go into one of these connectors. The wire checks out with a meter as a good ground and It may be a ground feference for the coolant temp sensor.

 

In addition, I have the o2 sensor out of the car as the other was physically broken. Shouln't this set a code?

 

Any help is greatly appreciated.

 

Lee

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That wire is probably disconnected on purpose, there is a pin on the ECM (J1C3) that is grounded if the car does not have air conditioning. Cars with A/C still have the wire in the harness, but it is left unconnected.

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Thanks for the reply. My esprit does have A/C though. I can verify if there is a pin in that position but I have no ECU pinout or connector info.

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My point is that it is normal for a loose black wire to be present.

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Sanj,

 

Thanks again for the info. I verified the entire circuit was intact by checking the codes w/ the ALDL, I realized that it took a long time to reach operating temp and the rad was warm very early indicating a stuck open t-stat or no stat. The engine relies on a bypass type stat so there is proper circulation at all times.

 

I removed the stat to find it was stuck about 1/4 inch open when fully hot. After I changed it, the fans started working properly. I suspect that the coolant temp sensor for the ECU was exposed to slightly cooler fluid due to lack of proper circulation.

 

I cannot stress how important checking codes, running the rad fans and engaging the A/C clutch is w/ the ALDL. The circuits are intact and both will operate properly if you hear them. The only caveat is that the coolant temp sensor could be a bit out of spec and this test may or may not include its verification. Although it is unlikely to be out of spec if there is no code present.

 

Now, does anyone out there have a weird tubular coolant level module? The wires were cut and spliced onto this module so I doubt it is stock. And it doesn't work anyway. The light is forever on grounding/shorting etc. I understand the Elise used a different style and maybe this is it??? No pics yet.

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