jeepwm69 7,206 Posted March 30, 2020 This yellow 06 I bought to fix and flip had the fan grounded so that it came on whenever the key was turned on. I figured the oil temp sensor on the bottom of the motor was bad. Yesterday I got the newly rebuilt engine in and cranked up. Runs great, shifts great. I took a jumper wire and ran it to ground, and then to the connector where the oil temp sensor plugs into the main harness. When I do that, the fan motor barely turns over for about 2 seconds, then stops. If I run that same jumper wire to the - wire on the fan, it comes on and spins full speed like it should. So obviously, there's an issue in the wiring harness somewhere between that connector that the oil temp sensor wire plugs in, and the fan itself. Am I correct that the oil temp switch grounds when it reaches a certain temperature? I'm thinking I could just run a jumper wire from the wire going to the oil temp sensor and run it straight to the ground wire on the fan. Would that work? Share this post Link to post Share on other sites
Melatv 774 Posted March 30, 2020 Hi Jeep: Check the continuity on the Y/G wire from the Oil sensor harness to the ECM 33 pin connector. 1 Share this post Link to post Share on other sites
shadetree 5,543 Posted March 30, 2020 3 hours ago, jeepwm69 said: This yellow 06 I bought to fix and flip had the fan grounded so that it came on whenever the key was turned on. I figured the oil temp sensor on the bottom of the motor was bad. Yesterday I got the newly rebuilt engine in and cranked up. Runs great, shifts great. I took a jumper wire and ran it to ground, and then to the connector where the oil temp sensor plugs into the main harness. When I do that, the fan motor barely turns over for about 2 seconds, then stops. If I run that same jumper wire to the - wire on the fan, it comes on and spins full speed like it should. So obviously, there's an issue in the wiring harness somewhere between that connector that the oil temp sensor wire plugs in, and the fan itself. Am I correct that the oil temp switch grounds when it reaches a certain temperature? I'm thinking I could just run a jumper wire from the wire going to the oil temp sensor and run it straight to the ground wire on the fan. Would that work? oil temp sensors are always hot, just like the neutral and reverse switches, when you ground them to the engine, thats what turns the dash lights on. so, you will need to check the power lead on the harness side that runs to the oil temp sensor, it should have 12 volts to it ?. Share this post Link to post Share on other sites
jeepwm69 7,206 Posted April 4, 2020 Did have continuity on that pin on the ECU, so service manual instructions said replace CDI. Luckily I had an extra CDI from a parts bike, plugged it in and the fan now kicks on when the oil temp sensor wire is grounded. So, bad CDI/ECU Thanks for the help! 4 Share this post Link to post Share on other sites
