2003 LQ4 Dual cooling fans always grounded
04-18-2017, 06:59 PM
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2003 LQ4 Dual cooling fans always grounded I added pins to C1- 42 and C2- 33 and was trying to verify that I could manually turn them on and off with VCM scanner and they are always grounded. I can cycle the AC clutch on and off manually but the wires added to 33 and 42 are always grounded till I turn the vehicle off. I did double check all the grounds(6 of them) coming off the ECM connectors and they were good. Not sure what I'm missing, from what I seen people add the wires to 33 and 42 and then that's it besides the adjusting on and off temperatures.
Last edited by daigs85; 04-19-2017 at 04:44 PM.
04-18-2017, 07:43 PM
#2
Theres a setting in the tune to tell the pcm how many fans. Most truck pcms are set to no fan, atleast most 03s were. If you have been playing with the on and off temps with the vcm editor im sure you seen it.
If that has been changed to tell the computer to control the fans, i would look at the coolant temp. If the sensor is bad or unplugged for that matter the fans will run full time. I believe the trans temp can do this also, as well as other engine/trans faults that will usually set a dtc.
If that has been changed to tell the computer to control the fans, i would look at the coolant temp. If the sensor is bad or unplugged for that matter the fans will run full time. I believe the trans temp can do this also, as well as other engine/trans faults that will usually set a dtc.
04-18-2017, 08:23 PM
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This is with the vehicle not running and cold, there are also no dtc's. I did change the tune from NO fans to two fans. I will check to see what the temperature sensor actually is cold and as vehicle warms up.
04-19-2017, 04:31 PM
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I don't have the fans in yet, I was verifying that the PCM could switch pin 33 and 42 before I went further with the install to confirm that things were working as they are supposed to. When I do install the fans I will use/duplicate 2005 Silverado coolant fan relay module.
04-19-2017, 05:16 PM
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Coolant temp and trans are all good and no DTC's. Is the computer looking for a certain resistance or some type of feed back from the fans and relays and maybe since there not seeing that this is why 33 and 42 are always ground out? Also since this van never came with electric fans is this all possible to add them? I haven't heard any one say that haven't been able to do this, usually its just add the 2 wires to the ECU, turn them on in the editor and add the hardware and ur set......
