Anyone with fan wiring schematic?
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 1,135
Likes: 17
From: NJ
Anyone with fan wiring schematic?
I am installing the new DeWitts fan assembly in my 99 C5 last night and I have a wiring question. The passengers side plug is a different color than the drivers side plug and I was wondering what is power and what is ground. Now I'm no idiot when it comes to wiring, the passengers side wires are black and white......obviously, the black is the ground and white is the power......RIGHT? Ok here is where it gets interesting. The drivers side plug is light gray and light blue......What is what?? If going by the plug on the passenger side, it looks like the light blue is the power.
If anyone has a wiring schematic for this I would greatly appreciate it.....alot.
If anyone has a wiring schematic for this I would greatly appreciate it.....alot.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
Fan wiring is confusing
First time I looked at the wiring for the fans, I thought ... WTF???? Makes NO sense ... but once you see it ... it's kinda clever.
What helps the most to understand the system is the following ....
When the fans are in LOW speed mode, the two fans are basically wired in series ... they both share the same power source and ground .... so effectively each fan is running off 6 volts of power. When the PCM commands HIGH speed mode, each fan is delivered its own power source and ground, providing each fan a full 12 volts of power.
In LOW, the LT BLU wire is hot, and the GREY wire is feeding the voltage through Relay 44 to the WHITE "hot" to the right cooling fan, which then grounds the fans using the BLACK wire.
In HIGH speed mode, the LT BLU wire is still hot, but relay 44 now grounds that fan directly to ground by switching the ground to a BLACK wire (Circuit 250) which goes directly to ground. The Right cooling fan in HIGH gets its power from relay 43 instead of being powered from relay 44 (the left fan) and is still grounded by the BLACK wire.
Kinda weird, but it works.
What helps the most to understand the system is the following ....
When the fans are in LOW speed mode, the two fans are basically wired in series ... they both share the same power source and ground .... so effectively each fan is running off 6 volts of power. When the PCM commands HIGH speed mode, each fan is delivered its own power source and ground, providing each fan a full 12 volts of power.
In LOW, the LT BLU wire is hot, and the GREY wire is feeding the voltage through Relay 44 to the WHITE "hot" to the right cooling fan, which then grounds the fans using the BLACK wire.
In HIGH speed mode, the LT BLU wire is still hot, but relay 44 now grounds that fan directly to ground by switching the ground to a BLACK wire (Circuit 250) which goes directly to ground. The Right cooling fan in HIGH gets its power from relay 43 instead of being powered from relay 44 (the left fan) and is still grounded by the BLACK wire.
Kinda weird, but it works.
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 1,135
Likes: 17
From: NJ
grey from car to black wire on fan
white from car to red wire on fan
light blue from car to red wire on fan??
I hope Tom DeWitt chimes in........I pm'ed him just in case.
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Former Vendor
Joined: Jan 2000
Posts: 5,593
Likes: 631
From: Brighton
The above schematics sound correct but just in case I would check it with a voltage meter.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
