Troubleshooting fans
Thread Starter
Drifting
Joined: Dec 1999
Posts: 1,751
Likes: 14
From: Wyckoff NJ
Troubleshooting fans
I have a 200 degree temp. switch wired so both fans go on,installed about 1.5 yrs ago.Recently the fans come on at all different temps,and when they do "service engine light" comes on.code 26,28.How can I diagnose the problem.What could cause this? bad: fan switch,ac pressure switch,relays,ECM???Thanks in advance
Instructor
Joined: Oct 2000
Posts: 206
Likes: 0
From: Nashville, Tn. 37211 TN.
Re: Troubleshooting fans (vettes)
May be the temp sensor for the ECM. The ECM stills controls the fans even with the other sensor. On my '85 it is located at the front if the intake manifold. Definately the first place I'd look.
[Modified by Camvette, 12:22 PM 5/23/2002]
[Modified by Camvette, 12:22 PM 5/23/2002]
Thread Starter
Drifting
Joined: Dec 1999
Posts: 1,751
Likes: 14
From: Wyckoff NJ
Re: Troubleshooting fans (ZylaRace)
26-Check EGR, Canister Purge and AIR pump relays with a digital Ohm meter. A resistance of less than 18 ohms indicates a bad relay. If OK, potential ECM failure.
28-Air conditioning Clutch relay and/or cooling fan relays. Check with digital Ohm meter, replace if less than 18 Ohms. If relays OK, potential ECM failure.
28-Air conditioning Clutch relay and/or cooling fan relays. Check with digital Ohm meter, replace if less than 18 Ohms. If relays OK, potential ECM failure.
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Re: Troubleshooting fans (vettes)
I'll presume that is less than 18 across the coil connections.
28 sounds like one of the relay's went bad. The fact of fans coming on at different temp make me think that also. If not check the wiring of the "new" circuit. (Main and aux fan coming on at the same time.)
28 sounds like one of the relay's went bad. The fact of fans coming on at different temp make me think that also. If not check the wiring of the "new" circuit. (Main and aux fan coming on at the same time.)
Thread Starter
Drifting
Joined: Dec 1999
Posts: 1,751
Likes: 14
From: Wyckoff NJ
Re: Troubleshooting fans (ZylaRace)
Last nite both fans on.I unplugged one fan relay at a time and that fan went off,when plugged back it it went back on.Does this mean the relays are ok.Should I just pick up a pair of relays and try this first before anything else.
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1st Gear
Joined: May 2002
Posts: 1
Likes: 0
From: watervalley ms
Re: Troubleshooting fans (vettes)
my dash speedometer is incorrect(digital) idle is rough,unable to throttle into ive changed
plugs
wires
cap&button
oxgn sensor
had MAP sensor checked
dash doesnt "light"up when lights on(or any other time)YET
cruise doesnt cruise
is these systems of ECM failure? : :confused:
plugs
wires
cap&button
oxgn sensor
had MAP sensor checked
dash doesnt "light"up when lights on(or any other time)YET
cruise doesnt cruise
is these systems of ECM failure? : :confused: