We have a 1998 Chevy Venture MInivan. It is coding P1651 saying FAN 1 RELAY...

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bonedocs4u

New member
...CONTROL CIRCUIT. What is this? We replaced the thermostat due to overheating and that is corrected. System pressures up nice now. This code P1651 has been cleared but it keeps coming back. It says two things: 1. Fan 1 Relay Control Circuit. 2. Fan on Relay Control. I cannot find what these are, where they are and how to fix them. I am losing my mind over this!! It seems to run great but I am concerned about it overheating, I am guessing this is caused from the previous overheating but that is my guess??? Any help would be appreciated.
 
a relay is basically a remote controlled low power switch. it is a coil when energized pulls a contact bar down closing the switch.

it is that way so you need little amperage to power the relay and a small switch to power the relay. when the relay closes it has bigger wires (to carrry more amperage) to higher drawing devices like the fans. the fans can draw up to 20 plus amps on control wires to the relay that would burn up because they are to small.
 
I am making some assumptions here so bear with me. Many GM fan systems are a 2 fan system that works 3 different ways. If one of the relays fails it can cause both fans to not work or work constantly. To check, switch Fan 1 and Fan 2 relay and see if the code changes to Fan 2. The relays will normally be in the same spot as the underhood fuses. Look for a "power center" cover or something similar.
 
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