Discussion
my ecu is switching the fan to ground,
if yours is the same you need to change the way you control the fan relays. Connect the 12 V feed permanently through a fuse and
run the control wire of the ECU to the Ground connection of the relays (it does really matter which pin of the 2 control pins of the relay is ground or positive 12V, they will work either way).
Then for the manual switch the same thing, run a ground wire to the switch and the output of the switch in parallel to the wire that comes from the ECU. Then you can always turn on the fans whenever you like.
if yours is the same you need to change the way you control the fan relays. Connect the 12 V feed permanently through a fuse and
run the control wire of the ECU to the Ground connection of the relays (it does really matter which pin of the 2 control pins of the relay is ground or positive 12V, they will work either way).
Then for the manual switch the same thing, run a ground wire to the switch and the output of the switch in parallel to the wire that comes from the ECU. Then you can always turn on the fans whenever you like.
Or install a separate mini relay connecting a ign switched live to the + side of the coil & one side of the load. Connect connect the other side of the load to the existing relay and the ecu wire to the ground side of the mini relay coil. This would mean that you would disturb the existing wiring loom the least. It is simple and I am considering doing the same on my car to switch the fans on based on engine temp rather than water temp in the radiator.
The information to switch the fans is taken at the engine Graham and not the coolant temp in the radiator. This is as it really should be in the higher powered SBC's too. Therefore there should be no reason to have additional switching. In fact, additional fan control and running could upset the GM ECU as the fan sensor doesn't just switch the fan, it combines with other parameters given to the ECU to alter the tune/running for the current conditions, giving protection!
We spend our hard earned on EFI engines as a forward step so why not allow the design engineers product do the job intended?
In addition Graham, the LS's use a more efficient method of engine cooling and do seem to run considerably cooler than SBC's....when plumbed correctly.
We spend our hard earned on EFI engines as a forward step so why not allow the design engineers product do the job intended?
In addition Graham, the LS's use a more efficient method of engine cooling and do seem to run considerably cooler than SBC's....when plumbed correctly.
Edited by 738 driver on Sunday 13th June 09:35
Correct me if I am wrong but as I see it Graham is trying to use the ECU to operate the fans Which as you say is the correct thing to do. However the wiring of this in an LS CONVERSION is not straightforward for a non electrical person. If the ecu switches to neg to activate the fans as my FAST one does and Spatz's one does then some extra wiring or loom mods will be required. Agueably the fan switch in the cockpit is not required when using engine temp rather than radiator temp to switch the fans. However in an LS conversion I would want to leave it in place and working rather than have a hole left in the dash. However the hole could be replaced by a light to indicate when the fans are running maybe?
Graham-P said:
Dave,
Good point, I seem to be losing buttons from the dashboard, that will give me two spare.......
When are you down this way next???
Graham
Unsure at the moment but should have an idea mid-week, been very busy....hopefully get a visit in too.Good point, I seem to be losing buttons from the dashboard, that will give me two spare.......
When are you down this way next???
Graham
Not forgotten compressor wiring either.
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