Jeep YJ LQ4 No Electric Fan

[Ratjeep]

Hello All-

I'm a new member (since yesterday!) working on a 1995 Jeep with a transplanted 2004 LQ4 and can't get my electric fan to power on through the ECU.

I'm using a Painless harness and Relay to power a single fan in my Jeep. I have verified all wiring and relay operation by grounding the relay to simulate a ground on pin 42 of the Blue connector of the ECU.

I have checked all grounds associated with the ECU.

I have attached my tune which I updated to a 2005 Hummer H2 yesterday complete with OS. I have both DTC's for both fans turned on with Fault reporting on and set my "on" temps to 200 Degrees F. My mechanical thermostat is a 187 degrees F unit.

I have scanned with FAN1 and FAN2 channels enabled in the scanner, they never come on.

I have turned the fan off in the DTC's, loaded that tune and ran the engine. Then I turned fan back on in DTC's, reloaded tune and ran engine.

While scanning I turned the fan on through scanner but it never indicated on or came on.

I was thinking of disconnecting the Speedo and Tech just to see if it would make a difference.

I'm lost?? Any ideas would be appreciated...

Are there any ECUs that won't power an electric fan?? Do I have one?? I figure it got to be an ECU problem..

My LTFT's and STFT's look kinda skewed from bank to bank, I built my own exhaust so I hope I got the O2 sensors positioned OK. I was thinking of swapping the O2 sensors to see what happens..

1995 Jeep YJ
2004 LQ4 6.0
2005 4L65-E
Ford 8.8
NP231C



2005 Hummer H2 Tune modified 3-8-2016B.hptNo Fans.Jeep.hpl

[Jon S.]

Your Fan Type is set to "No Fans". If you are using a single fan you can set this to either "2 Fans" or "Aux Fan".

[Ratjeep]

Thank You Very Much!