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Discussion Starter · #1 ·
Hello all!

( 94 Impala SS ) primary and secondary fans both are running continuously when car on… what could be causing this?

when I turn the car on, both fans start right up.

relays and fuses are good…
 

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Check the H2Opump temp sensor.
If you want to try throwing ONE part at the problem, before you just replace the H2Opump temp sensor, check the very thin & brittle 28 year old wiring leading to the H2Opump temp sensor.
 
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Discussion Starter · #3 ·
One more thing… I pull the connector from the water temp sensor and the fans both keep going… and when I pull the connector off, the engine idle changes for a few seconds and then stabilizes
 

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Hello all!!
I have a 94 Impala SS #1577…
I’m looking for ODBI scanner tool… that reads our cars… which one works?
(Besides the Innova)
Did you ever get the scanner ?
Without you run a very good chance of burning time and money.
The fact that the engine running changes when you unplugged the wp sensor " suggests" that may not be your issue.
 

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There were a few mentioned in the last thread.
The old OTC Enhanced or 4000 Enhanced will read data and codes PCM , SRS , ABS on a 1995 Impala OBD1 .
Rather than talk out my ass , I just went downstairs and fired mine up .
They can be found used for cheap
Electrical wiring Telephony Gas Office supplies Audio equipment
White Motor vehicle Font Automotive tire Automotive exterior
Font Line Material property Measuring instrument Gas
Gadget Musical instrument accessory Electronic instrument Font Musical instrument
Office equipment Fluid Gas Font Electronic device
Automotive tire Motor vehicle Font Material property Gas
Font Electronic device Technology Parallel Display device
 

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1996 Impala SS
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Pull both Fan relays out, you’re going to see that the plastic housing fuse holder is melted, to cure/fix this problem your going to need dual fan relay kit from Gary @ innovative wiring. The problem here is that GM used undersized wires for the fans, and in turn the wiring gets very hot heating up the connector, up in fuse housing and then melting the area where the metal tab of the wiring hooks up housing in the plastic fuse box housing. “Tip” Turn your car on and move around both fan relays pressing down on them.

This is what it will look like possibly worse..
Rectangle Font Gas Technology Machine
 

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The problem here is that GM used undersized wires for the fans, and in turn the wiring gets very hot heating up the connector, up in fuse housing and then melting the area where the metal tab of the wiring hooks up housing in the plastic fuse box housing. “Tip” Turn your car on and move around both fan relays pressing down on them.
This would be good advice IF THE FANS WERE NOT WORKING. BUT
primary and secondary fans both are running continuously when car on… what could be causing this?
More probable causes for fans running continuously are temperature sensor failure and damaged wiring.

The OP can check that the fan relay coils are being grounded by the PCM control wire. If they are the focus should be on PCM wiring and the temperature sensor.

The TSB was for cars that idled all day with the primary fan cycling all the time. The high probability reason for melted fan wiring in normal use cars is malfunctioning fan motors drawing too much power. The fan fuses are large or the fan motors would blow them during spin up(starting). When a motor begins to fail it draws too much power all the time but not enough to blow the fuse. The wiring will melt under these conditions.

Fans running continuously would be easier to diagnose with live data. It can be diagnosed with a multimeter(ohms and volts).

Fans run continuously=check temp sensor and wiring most of the time. Shorted relays, bad PCM, and other issues have a low probability.
 

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Was there a second TSB ?
The first was directed at SEO cars

Bulletin No: 53-62-04 Date: November, 1995 Subject: Engine Overheats (Install Cooling Fan Relay Kit) Models: 1994-96 Chevrolet Caprice with SEO Option

As for why, how many faults cause the PCM to turn on fans,,,,,, not just coolant sensor out of range ,,,,,,,,
 

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I will have to dig through my TSB stuff Gerry. My relay did melt the fuse block and dealer did install the outboard Relay GM developed, at no cost. I have since installed Gary's dual harness, but I believe it was a prototype as mine has a relay box installed near core support. Instructions had it in front bumper but PIA to access vs the firewall where GM and now Garys kit installs

My Kit from Gary may have been intended to both deal with under hood heat exposure to relays and also bigger wire. It used the 4 (big pin) relays.

96 SS, dual fans
 

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BALLSS do you remember this:
Font Cable Slope Technology Gadget


 
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