99-02 Silverado Electric Fan Conversion Wiring Diagram – Visit my Facebook page for my extensive YouTube channel for new pictures and how-to video tutorials – Email: brendan@
Below is some information for LT1, LS1, Vortec 4.8, 5.3, 6.0 cables. That should be enough to get you started in the right direction. Some of these I have pictures of complete wiring harnesses that I have modified for easier installation. I have a lot of pictures, please be patient while it loads. If you find this information useful or have suggestions for what I should add, please let me know and I’ll do my best to do so. My goal is to help hobbyists be able to do their own makeovers. I just hope you send me the PCM in due course. I do not charge any information fees.
99-02 Silverado Electric Fan Conversion Wiring Diagram
The example schematic is similar to what you see on the following pages. This can help you learn how to read schematics
Pcm Electronic Fan Control…
Battery Connection 12v+ – The computer requires a permanent connection to the battery. This way the PCM can remember the learned engine information over time. This includes idle speed control, fuel trim and transmission tuning. It is very important that the battery’s hot wire (usually orange) stays hot at all times.
Kei 12v+ Connection* – The PCM also gets 12V+ from the KEI HOT power supply. This is what “drives” the PCM. It is important that this all-important thermal power, along with power to the injectors, coils, etc., stay hot when the engine starts. Some critical accessory locations are not hot on startup. This also includes older vehicles with ignition points. Even the wires on some coils go dead on start up. This is because when the coil is activated, it is boosted to 12v+ through the R terminal on the starter solenoid. When activated, power is fed back to the coil through a resistor, reducing the voltage to 6 volts.
Fuel Pump Relay Control – The computer on the GM fuel injection system is designed to control the fuel pump relay. The computer does this by providing a 12v+ (positive) signal to the relay. This signal is only present for two seconds when powered on. The fuel pump continues to run while it is cranking. Only when the PCM reads that the engine is turning over will the PCM command it to turn back on. So, if there is a bad crankshaft sensor condition, the fuel pump will turn on, off and not on at start up.
Brake Switch Signal – For automatics with a lockup converter, the PCM requires a signal when the brake pedal is depressed. However, it requires a signal that is the opposite of how brake lights work. The PCM requires a constant voltage of 12v+ on this line when the brakes are not applied, and an OPEN circuit when the brakes are applied. If your vehicle came with a locking transmission to begin with, you probably already have a suitable normally closed switch installed on the brake light switch. If you don’t, you can use relays to accomplish the same thing. On most relays there are 5 terminals, 2 of which open the relay when ground/power is supplied. Then there is a normally open leg and a normally closed leg on the relay and power supply. By applying 12v+ to the power leg and connecting the brake switch signal wire to the normally closed leg you can now send the correct signal to the PCM. When the brakes are applied, 12v+ goes to the brake light, touch this wire and run it to the relay to turn on the relay. This will cause the normally closed branch to open, turning off the 12v+ signal to the PCM. When you release the brake pedal, the relay closes and then supplies 12v+ to the PCM.
Need 2001 4.3 Ecm Pinout Diagram
VSS Signal – This line is a 4000 pulse per mile signal from the PCM, which is used by some aftermarket speedometers. This is also used in the electric cruise control boxes used on General Motors cars and trucks in the early 90’s. The PCM can be programmed to match the tire size and axle ratio you are changing, so the signal is calibrated. Chrysler/Jeep vehicles typically require a signal of 8000 pulses/mile to trigger the speedometer.
TACH signal – On a 1993 LT1 with a splitter, it comes from the negative side of the coil. Later LT1 and LS1, Vortec 4.8/5.3/6.0 This comes from the PCM which generates this signal for the auxiliary tachometer. The standard LS speed signal is a 4 cylinder type signal. This can be programmed as a signal for 4, 6 or 8 cylinders. Some 2003+ LS PCM’s tach signal is not strong enough and needs to be amplified, see this link.
Fan Control 1, 2 – GM PCM usually controls electric fans, usually 2. The PCM will provide a (negative) or GROUND signal to open the fan relay. You cannot connect the fan control PCM wires directly to the fans. You have to use a relay.
The wires to terminals 30 and 87 should be 10-12 gauge to handle the cooling fan current. Terminals 85 and 86 can use shafts 16-22. The relay coil draws less than 1 amp. Make sure the cooling fan has a good ground, also make sure there is a good ground from the battery side (-) to the frame.
How To Disable Luxx Series Cooling Fan
Use this diagram to connect a two-speed fan, such as a Ford Taurus fan. In this schematic this is opened on the right using a 5 terminal relay. When the HIGH gear is activated, it cuts power to the first relay. This prevents power from being applied to both fan wires at the same time.
If you want the fan or fans to turn on along with the A/C compressor, you can use the following wiring to do so. The “TO CONTROL THE FAN RELAY (-)” label can be connected from the PCM to the FAN relay. This way the PCM can still control the fan when the A/C is off or the A/C is commanded to be on and the fan starts up immediately. Just thought I’d post it in the archives. After reading all the various posts about the LS1 fan graph and correcting the inconsistencies and cleaning it up for us simple non-engineer types, oh wait, I’m an engineer
That’s fine of course. Got one for someone who just wants to run fast all the time? I don’t care about low speed vs high speed, and it seems to twist the wiring a bit.
Depending on the amount of current drawn by the fan, you may need to use 2 relays to get enough current capacity. If you do this, the connections are the same except for terminal 87, connect the + side of one fan to one relay and the + side of the other fan to the other relay.
Direct Fit Electric Cooling Fans For Chevrolet/gmc Full Size Trucks And Suvs
This is a 97 Iroc fan, or possibly a 94-96 LT1 fan, 2×12″.
It’s an interesting idea, and I’m guessing you don’t really need a two-speed setup. If the two fans draw 40 amps, you should probably use two 30 amp Bosch relays, if you can find a 40 amp relay, only one will work.
Question G-Body, most charts I’ve seen have the “always hot” connection 30 instead of ignition, I was wondering, if it’s really hot, does the computer run the fan when you turn it off? So should it be associated with “always hot”?
After thinking about it, you could probably be better off just running two different circuits and using two 20 amp fuses:
Nbs (99 07) Silverado Sierra Suburban Tahoe Integration Harnesscurrent Performance Wiring
I have a 2002 LS1 fan and I plan to use the same wire as the fan, it’s thick, 10 gauge I guess.
The computer runs the fan…but turns off the ignition…so does the fan control…so no real need to run hot all the time…that’s why it’s IGN+ 10A for me…but it really doesn’t matter… Same in both directions. Actually, my truck is wired to BAT+…not IGN+, and it still turns off the fan as soon as I turn off the car…so I’m assuming the computer stops the fan circuit IGN+ as soon as you drive. Thanks for based on my point…I also wondered if there was a way to make the computer run the fans until it actually cools down…not just when you shut down the engine.
Sorry for the confusion, I actually meant to say “hot all the time”, although as Junkinson said, it doesn’t really matter in the end. As far as I know, the PC should not be able to turn on the fans if IGN is off. That way, it won’t run the fan until the battery dies and you get bogged down. When I wrote that, I was looking at my converted notes because I linked my
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