Thread: Coolant temp circuit.

So Ive had a few issues with my B13 turbo swap. I got it to start after replacing the dist. rotor. Now its only starting with throttle open. It bucks and runs rich. I pulled ecu codes and got knock sensor and coolant temp. So I pull the KS sensor to check voltage and continuance. probe harness...nothing. turns out it was missing a pin. Now I just need a new plug to splice in

Now I go to check coolant temp sensor voltage with key on. Nothing. checked voltage, resistance beween pins etc. I check the sensor resistance since its brand new, its good.

So the whole CTS circuit is dead. I tested 2 ecus so that is not the issue. Has anyone ever encountered this issue? Can I rewire it directly back to the ecu pins?

My mechanic is always dissing the Nissan harnesses. You might wanna rig up a direct wire. I think you have got it. That would totally explain the weird starts.

from what ive found the harness has two wires. One is 5 volt and the other wire is for signal return to the ecu. I was told it tees into another spor in the harness before going to the ecu. im posting from my phone so i cant download or view the pics from fsm unless theyre hosted. hopefully someone has a diagram. Its for a 91 ser. also what years did the harnesses change.

I'd check for continuity between the F222 connector and the sensor and then between the F7 connector and ECU connector.

That should determine if there is a break and if so what section. A visual check of the suspect wire should reveal any breaks. If that doesn't turn anything up then I'd just splice in a new wire for that section.




Edit: Diagram is from a 1991 FSM

Thanks man. Ill try this tomorrow since I really dont feel like putting a new harness in.

found the harness issue for the coolant sensor. Now I just need to get a knock sensor plug.

got the issue fixed. Thanks AngrySquid for the pic.

What ended up being the problem, I'm guessing it was pretty minor?

reaallly stupid actually. the f7 connector was loose. btw ill om you. i work and live in monroe wa.