1996 Corvette LT-1. Can the 5 pin cooling fan relay be used in place of the 4 pin relays? Schematics look the same except the 5th pin.

Since you did not list your year, 2 or 4 wheel drive, denali..etc.. this info wil be generic to a 2009 envoy 2WD..

Blower Motor Resistor

https://www.oreillyauto.com/shop/cooling---heating-16773/blower-motor-resistor-12386/1996/chevrolet/corvette?viewName=redirect%3A%2Fshop%2Fcooling---heating-16773%2Fblower-motor-resistor-12386%2F1996%2Fchevrolet%2Fcorvette


https://www.oreillyauto.com/shop/lighting---electrical-16777/relays-16479/a-c-relays-16537/blower-motor-relay-11581/1996/chevrolet/corvette?q=Blower%20Motor%20relay

please mark as helpful.. thanks

2 fans behind RAD
is 1MZ engine, the 5s is different. 1fan

1mz engine has 2 switches.
the twin fan engine is 1MZ (bingo)
the 1mz has 2 switches. a real pain when know one posts engine.
FSM data: ECT switches.
sw1--opens >208f closes < 190f
sw2.-opens >199f closes < 181f

i see the PCM has CF cooling fan control too.
my online source has 30+ pages of schematics
and covers it all but skips the fan wiring.
on the right fender fues box is the 4 or more fan /AC relays.
if you unplug the ECT sw1 or 2, or the relays im sure
you will find how is missing up and work from there.

it looks to me , (A/C drawings) that the PCM and A/C amp can both
control all fans but has 2 ways to do that.
PCM can see engine heat (ECT EFI) and activate fans when engine overheats, (normal at long idle times as stop sigs)
and the 2 , SW 1,'2 temperature switches are a backup i think too
all this and is staged, first 1 fan then next,
too bad the fan relay schematic is missing..

The engine temp sensor sends a signal to the computer and the computer grounds the fan relay when it is needed.
I'm showing 6 relays on the firewall under the windshield.
The two on the right side are high and low radiator fan relays.

U have an electrical issue. If water pump was failing then how in god's creation could the two fans cool the engine down? Check out the circuitry that controls the normal fan operation and you will take care of the issue. Till you find the problem just hot wire the fan motor with an on/off switch.

book shows only 4 pins. That is all you need to run a relay. See my notes at http://www.fixya.com/cars/r6022358-relay_check and try a different parts store.

On this vehicle there are 3 cooling fan relays and three fuses for the cooling fans.There are 2 in the under hood fuse panel and 1 in the instrument panel.You need to check the fuses and make sure they are all good.They get there input via the coolant temp sensor for the computer which in turn signals the cooling fan relays to turn on the fans.The other thing with the a/c clutch coming on and off.If the a/c system is low on freon this will cause the clutch to cycle more.If you can get a scan tool you need to monitor the coolant temp sensor to see if it is reading the same as the temp on the temp gauge.The other thing you an do is check for codes.Hope this helps and let me know what you come up with.

Trouble code P1652 means: Cooling Fan 2 Relay Control Circuit Malfunction

I would start by checking power supply to the cooling fans,making sure the coolant system is full,& using a scn tool to verify the proper operation of the cooling fan system.Here is some info to help you.

The Powertrain Control Module (PCM) controls the operation of the cooling fans. This is accomplished by providing a ground path for the cooling fan relay coils within the PCM. The relay contacts will close and complete the circuit between the fusible link at the battery junction block and the fan motors. Whenever there is a fan ON request both fans will be running.

Power for the fan motors is supplied through a fusible link at the battery junction block. Battery positive voltage is applied to the cooling fan relay contacts and coils. The cooling fan relays are energized when current flows through the relay coils to ground at the PCM. The cooling fan relay #1 control circuit is used for low speed cooling fan operation. The cooling fan relay #1 control circuit and the cooling fan relay #2 and #3 control circuit are both grounded for high speed fan operation. The cooling fan relay control circuits are monitored by the PCM. Before using the Electric Cooling Fans diagnostic tables be sure to perform the Powertrain On-Board Diagnostic System Check. If diagnostic trouble codes P1651 or P1652 are present, use the appropriate DTC diagnostic tables prior to performing Electric Cooling Fans diagnostics.

Important: When certain Diagnostic Trouble Codes (DTCs) are present, the PCM may command the cooling fans to run all the time. It is important to perform the Powertrain On-Board Diagnostic System check prior to diagnosing the engine cooling fans.The PCM will complete the ground path for cooling fan relay #1 under any of the following conditions:
- When engine coolant temperature exceeds 105°C (221°F)
- When A/C is requested and ambient temperature is greater than 10°C (50°F)
- When A/C refrigerant pressure is greater than 190 psi (2 volts)

For high speed cooling fans operation, the PCM will delay control of the cooling fan #2 and #3 relays for 6 seconds. The 6 second delay ensures that the cooling fan electrical load will not exceed the capacity of the system. The PCM will complete the ground paths for cooling fan relays #1, #2, and #3 under any of the following conditions:
- When engine coolant temperature exceeds 113°C (235°F)
- When A/C refrigerant pressure is greater than 275 psi (2.9 volts)

If a problem that involves the low speed cooling fan relay control circuit (cooling fan relay #1 control) exists, DTC P1651 should set. If the problem affects the high speed cooling fan relay control circuit (cooling fan relay #2 and #3 control), DTC P1652 should set. A problem with the ECT sensor should set DTC P0117, P0118, P1114, or P1115. Any of these DTCs will affect cooling fan operation and should be diagnosed before using the Electric Cooling Fan Diagnosis table. The Electric Cooling Fan Diagnosis table should be used to diagnose the PCM controlled cooling fans only if no DTC is set.
Hope this help to solve your poblem (remember rated and comment this help).

are the cooling fans working?have seen cooling fan relay problems with these vehicles..located under left headlamp..riveted in place..remove 2 bolts on top of headlamp and 2 nuts behind near air cleaner top housing..pin 4 of connector has battery power on it..pin 1 is ground..pin 3 is output..jump pins 3 and 4..fans should run..if they do,most likely relay is bad..but make sure fans are coming on first..let me know

Cooling fan relay would be a good starting place.

check for battery power at pin 4 of rad fan relay connector..ground at pin 1..jump pins 3 and 4..fans should work..if not,check harness about 3-4 inches away from relay connector..have seen these corrode..if fans work,the engine controller may not be grounding relay..any codes in engine controller?engine light on?