[Dhealy3154]

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…

 

[Marky Dissod]

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.

 

[Dhealy3154]

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

 

[BALLSS]

both fans should come on when you unplug the WP temp sensor. Markys suggestion is what I would do after carefully inspecting the wire/connector to that sensor

 

[95wagon]

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.

 

[Dhealy3154]

Can you recommend a ODB1 scanner that’s not the INNOVA 3123 GM OBD1 Code reader ?

 

[95wagon]

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

 

[Dhealy3154]

Thank you for the info 95wagon

 

[Dhealy3154]

Thank you all for your info and ideas.

 

[BALLSS]

scan9495 is a free download but requires a "cable" to connect PC to car

 

[95wagon]

scan9495 is a free download but requires a "cable" to connect PC to car

Absolutely, many ways to do this.

The one added advantage to something like the old OTC , is the ability to look at the ABS and SRS too.

 

[toonwarrior]

EEhack also another great free tool and frequently updated. Can adjust parameters with the car running also to hone in on the issue.

 

[1Slammed96SS]

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..

 

[BALLSS]

^^^, GM had a TSB on this and offered a remote fuse/relay but just for the primary fan. Garys kit is for both fans

 

[Z09B4U]

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.

 

[BALLSS]

GM felt it was a big enough problem they issued a TSB so it was way beyond fleet use cars.

Not only a TSB but a fix removing the relay from the underhood box and using heavier gauge wire

Op's issue is more likely faulty temp sensor

 

[95wagon]

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 ,,,,,,,,

 

[BALLSS]

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

 

[Z09B4U]

BALLSS do you remember this:

What is this relay for?

Hey guys, Found this relay in a box of parts today and I don't know what it is for. It must have came with a car because I didn't buy it. Anyone have any idea what it is for? The number on the sticker is 12137339 but I couldn't find anything when I searched for that either.

www.impalassforum.com

 

[Z09B4U]

TSB 53-62-04
1994-96 Chevrolet Caprice with SEO Option
Some owners may comment that the engine overheats. This condition occurs only in heavy duty operation, such as police or taxi use.

http://www.skymagik.net/storm/cars/tsb/b-body_536204.pdf