fan relay wiring 91 z28
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Junior Member
Joined: Feb 2010
Posts: 89
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From: stockton California
Car: Gone
fan relay wiring 91 z28
can anyone help rewire my 91 z28 tpi dual fans to original relay. currently running on a toggle switch, switch is hooked up to fuse box it melts after awhile thats why i need help rewiring it. no ac
Supreme Member
Joined: Jan 2006
Posts: 3,341
Likes: 10
From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Fan Plan
The PO probably jerry-rigged the deal because he didn’t know how to repair it.
You need to find out if the fan relay(s) is being energized.
The fan relay is on the left firewall.
It’s the one nearest the booster.
Make sure the FAN fuse in the fuse block is good.
Then you can make sure the fusible link is good.
Then using a voltmeter or test light (the type for testing for voltage, not a continuity tester) see if there is power on the orange wire at the relay.
You can test much of the circuit by having the key in the RUN position then grounding pin B of the ALDL (Assembly Line Diagnostic Link).
When you ground it the fan relay should energize.
If it doesn’t you can repost for repair information.
If it does connect the fans + leads to the relay output.
If the relay doesn’t energize when the engine is hot you can test and replace the Coolant Temperature Sensor.
For the long run you might want to replace the relay with a high capacity one for longevity.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If You’re Passed By Your Own Tire On The Track, It’s Time For A Pit Stop
.
You need to find out if the fan relay(s) is being energized.
The fan relay is on the left firewall.
It’s the one nearest the booster.
Make sure the FAN fuse in the fuse block is good.
Then you can make sure the fusible link is good.
Then using a voltmeter or test light (the type for testing for voltage, not a continuity tester) see if there is power on the orange wire at the relay.
You can test much of the circuit by having the key in the RUN position then grounding pin B of the ALDL (Assembly Line Diagnostic Link).
When you ground it the fan relay should energize.
If it doesn’t you can repost for repair information.
If it does connect the fans + leads to the relay output.
If the relay doesn’t energize when the engine is hot you can test and replace the Coolant Temperature Sensor.
For the long run you might want to replace the relay with a high capacity one for longevity.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If You’re Passed By Your Own Tire On The Track, It’s Time For A Pit Stop
.
relay dont work 
Member
Joined: Jan 2007
Posts: 446
Likes: 1
Car: 87 Camaro
Engine: 305 LG4 (H)
Transmission: 700r4
Axle/Gears: 2.73
Re: fan relay wiring 91 z28
I would never run anything that draws that many amps directly through a switch. Wire it back up to stock and see if it works. Find a wiring diagram and make sure everything is correct at the relay, thats usually where most wiring mistakes are.
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Supreme Member
Joined: Sep 2002
Posts: 9,192
Likes: 19
From: Cary, North Carolina
Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: fan relay wiring 91 z28
You could just run a seperate fan controller. Most auto parts stores sell them - anywhere from $35 - $100+. They are easy to wire, probe the radiator rather than the block so no messing with coolant in the face, and many brands available with many options. I run Flex-a-lite from Summit, best $100 I ever spent. Fully adjustable temp settings, options for manual on/off switches - really nice unit. Took 1 hour to install - no need for any of the factory stuff (relays, switches, etc), comes complete.
Junior Member
Joined: Mar 2017
Posts: 91
Likes: 20
From: Phoenix, AZ
Car: 1991 Z28 5spd
Re: fan relay wiring 91 z28
Just in case you need it, these are from my 91 GM service manual. This shows a little bit more detail, If it helps.
Last edited by jczoka; Jul 29, 2020 at 10:21 PM.
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