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Working on my 84 crossfire motor and need to replace the ECM coolant sensor mounted on the front of the intake. I purchased the AC Delco 213-52 replacement sensor recommended by GM as a better replacement than the original. The new sensor comes with 2 wires vs the single wire sensor. The instructions provided are worthless… has anyone installed this on their car and I’d so how did you wire it up? I found a few threads discussing replacing the sensor but nothing about the additional wire. As a former electronics technician in the military my instinct is to connect one wire to ground and one to the original feed wire. Any assistance greatly appreciated.
Thanks Tom
The coolant temp sensor (the one in the front of the intake that points towards the fan) is a 2 wire sensor. The ecm feeds it 5 volts and then it measures what voltage is returned. Wiring colors look to be black and yellow.
Thanks Buccaneer, appreciate the quick reply. Ex-X-Fire, my car has the original one wire connector and sensor which is what is shown on your schematic. Yellow wire to ECU and grounded through the threads to the intake. Which by the way is one of the ways to have issues with a sensor is to put thread sealant on the sensor preventing it from grounding.
Ok so I got this 84 running and monitoring with WIN ALDL. I have 2 issues, TPS voltage high which is a bad sensor as it’s original and voltage is stuck at 4.89v, reference signal good.
However the other issue really has me scratching my head. Earlier in this thread I asked about replacing the one wire sensor with the newer style two wire sensor. My FSM shows a black and yellow wire from the sensor to the ECM however my car only had the one wire which is brown. But here’s where the confusion starts, pin 4 on my ECM black connector is yellow per the FSM but when I run a test lead from the brown wire at the temp sensor connector (disconnected from sensor) and measure resistance from the brown wire to the yellow wire on the ECM I get 6K ohms. According to the FSM it should be a straight run with close to zero ohms to allow for wire resistance. Does anyone here have an 84 with the one wire sensor and if so, is the wire to the sensor brown? As the color of wire changes on my car it has to be going through another connector somewhere… help!
thanks Tom
My original coolant sensor connector and wire
Some additional data that may be related to the two issues… TPS 5v ref signal is good and variable resistor range in sensor looks good however the black ground wire shows an open circuit to ground which would explain why the TPS isn’t working. The FSM wiring diagram shows the ground shared between the coolant sensor ground and the TPS ground. Both sensors share the same harness so I am thinking there’s another inline connection somewhere, perhaps the bulkhead connector though I haven’t had a chance to get that far…
A one wire coolant temp sensor for the instrument cluster ( dark blue )
A two wire coolant temp sensor for the ECU ( Yellow + black )
A one wire coolant temp switch for the fan ( brown )
@JoBy thanks for the reply. Yes I have 3 temp sensors. I have a blue one wire on the drivers side of the block which is for the dash. I have a brown one wire on the passenger side of the block which is for the Fan and I have a brown one wire on the front of the block below the thermostat housing which feeds the ECM. Therein lies my problem, I don’t have the 2 wire yellow/black as the FSM shows and the wiring harness and sensor I removed looked original. I bought the car from the original owner so I know the history of the car well and it appears to be bone stock with most all f it’s original parts.
Last edited by 84C4Tom; Sep 8, 2024 at 07:53 PM.
Reason: Sp
Figured it out! Took a razor and began cutting open the wire loom to see colors of wires. Turned out someone switched the A\C compressor switch plug with the coolant temp connector plug, they are both in the same harness. FWIW, I bought this car not running from a retired Medical Doctor and the last time he had it on the road was 2002. Lord only knows the history behind how it got swapped but it was great to see those yellow and black wires peeking out at me 🙂
84 CFI ECU Coolant Sensor
