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Discussion Starter #1 (Edited)
I was going through a rather involved snap on professional scan tool that allowed me to do function tests and take over control of certain systems. Couldn’t get any B+ voltage out of wiring harness connector during KO step one, so I guess I need to check the physical wires continuity, which means disconnecting the C2 connector from the pcm and doing the tone / continuity test on the wire itself to see if I’ve got a broken wire.
I’ll let you know the outcome.
Oh. And BTW...
I also couldn’t get Fan #1 to come on (small one on passenger side) during the relay test. Is that indicating a bad relay or is that indicating a bad fan motor.
I’ve seen that fan run when the A/C is on a while ago so I’m pretty sure it still works.
Thank you all for any and all suggestions, advice and information.
I appreciate your time!!
 

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Discussion Starter #3
Disconnect the coolant temp sensor on the front of the water pump. That should cause the PCM to turn on both fans.

Ken
Thank you Ken !
That’s the exact kind of information that makes life 10 times easier when troubleshooting problems like this with these older B Bodies...
I appreciate your time and effort in responding
 

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Discussion Starter #4
Last time I looked at the knock sensors the one on the drivers side had a poor to loose connection with a connector that looks like it should be replaced. Knock sensor 1 is on the drivers side correct ?
Any help is appreciated greatly.
Thank you ahead of time for any and all responses !!!
 

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Bank 1 sensor 1 is the driver side upstream sensor, bank 1 sensor 2 is the drivers side downstream sensor, bank 2 sensor 1 is the passenger side upstream sensor, and finally bank 2 sensor 2 is the passenger side downstream sensor.

This is assuming a 96 vehicle, if 95 and earlier you only have two sensors so bank 1 is driver side and bank 2 is passenger side.
 

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Discussion Starter #7
Bank 1 sensor 1 is the driver side upstream sensor, bank 1 sensor 2 is the drivers side downstream sensor, bank 2 sensor 1 is the passenger side upstream sensor, and finally bank 2 sensor 2 is the passenger side downstream sensor.

This is assuming a 96 vehicle, if 95 and earlier you only have two sensors so bank 1 is driver side and bank 2 is passenger side.
Thank you 4x4 for the informative response. That was exactly what I needed to know in a precise and concise format.
I appreciate the time and effort in responding!
I hope you have a great tomorrow and beyond...
 

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Discussion Starter #8
Oh ****, my bad. LOL. Guess my mind is still on my new CAT's and 02 sensors I just swapped out.
No worries 4x4...
I’m confused most of the time on my own LOL...
Thank you for taking the time to respond.
It’s greatly appreciated...
 

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Discussion Starter #9
KNOCK Sensors. Not oxygen sensors. Knock.
Still, driver side should be 1, passenger should be 2.

If, after disconnecting H2Opump temp sensor, one of the fans does not turn on, swap the fan relays by the windshield wiper motor.
(If they're still in the box, relocate them outside the box when you get a chance. If the floor of the box underneath the relays looks cooked, relocate the relays immediately.)
If the OTHER fan decides not to run, replace the fan relay.
If the SAME fan decides not to run, replace the fan motor.
If BOTH FANS decide not to run, replace fan motor AND relay.
Once again saved by the ISS forum...
Thank you Marky for the information, that’s exactly what I needed to know in determining why the fan wouldn’t cycle on...
And how to fix it...
As usual your responses are accurate concise and to the point with all the relevant info and advice.
I appreciate the time and effort in responding to my question.
I hope you have had a great day today, and an even better tomorrow... 👍
 

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Discussion Starter #12 (Edited)
Disconnect the coolant temp sensor on the front of the water pump. That should cause the PCM to turn on both fans.

Ken
I tried that Ken, the car hesitated to start and neither fan came on...
I have voltage at both the dual harness connector contacts that the gray fan harness plugs into so I’m sure I have a bad motor.
I ordered an ACDELCO OEM replacement passenger side fan motor from CARID today.
$60.99
I noticed there doesn’t seem to be a connector going into the existing fan motor. Just wires going up into it.
Are there in fact, plugs that go into the motor under the rubber plug the wires go up into ?
Or are they hardwired in and I’ll need to get a pigtail connector since the replacement motor takes a plug...
I’ll call CARID in the morning to ask about if I’ll need the plug to connect it with.
Thank you for any and all help or advice.
I appreciate it !
 

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Discussion Starter #13
KNOCK Sensors. Not oxygen sensors. Knock.
Still, driver side should be 1, passenger should be 2.

If, after disconnecting H2Opump temp sensor, one of the fans does not turn on, swap the fan relays by the windshield wiper motor.
(If they're still in the box, relocate them outside the box when you get a chance. If the floor of the box underneath the relays looks cooked, relocate the relays immediately.)
If the OTHER fan decides not to run, replace the fan relay.
If the SAME fan decides not to run, replace the fan motor.
If BOTH FANS decide not to run, replace fan motor AND relay.
Once again saved by the ISS forum...
Thank you Marky for the information, that’s exactly what I needed to know in determining why the fan wouldn’t cycle on...
And how to fix it...
As usual your responses are accurate concise and to the point with all the relevant info and advice.
I appreciate the time and effort in responding to my question.
I hope you have had a great day today, and an even better tomorrow... 👍
I disconnected the water pump temp gauge and neither fan would run, swapping relays didn’t change anything so the relays are good. All the fuses were good also.
I checked for B+ voltage at the gray connector and have voltage on two of the four pin outs so I’m sure it’s the motor.
Thank you for the advice on the relays but I didn’t get the expected result when I disconnected the temp sensor plug.
 

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On your Fans....

Gary sells some nice replacement Harnesses if you need them and it sounds like you may need the fan to fan harness. He also has a good "fan testing" process you can follow there....

http://innovativewiring.com/?page_id=266

On your Knock Sensors....

Yes this is a FBody sight but tons of good info that is often applicable to our cars. I was just looking at it last night for some info on testing the coil. While they only use 1 KS, the info they have here could be used for our cars as well. Things like how to actually test if your KS is even ok are very applicable here and helpful...

4th Gen LT1 F-body Tech Articles

Hope this helps and doesn't confuse you, a lot of times you can stumble on Great info from other sites/forums with a Google search. I did just that when trying to find info on "how to test an LT1 coil".
 

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I meant disconnect while the engine is running. Yes the car will be hard to start if disconnected when the engine is off.
If you have seen a fan running it should have run with the connector disconnected. How long did you wait with the engine running?

Ken
 

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Discussion Starter #16
I meant disconnect while the engine is running. Yes the car will be hard to start if disconnected when the engine is off.
If you have seen a fan running it should have run with the connector disconnected. How long did you wait with the engine running?

Ken
Ahhh...
OK. Well that explains that from both you and Mark.

I didn’t wait long. I was doing stuff with my EVAP system that’s been giving me nightmares also so I wasn’t trying to get the engine compartment too hot.
I switched the fan on using the Solus SnapOn scanner to activate the fan circuit, I had B+ voltage coming out of the connector going into the questionably fan, so it has to be the motor. I have one on its way, it should be here Friday...
Thank you for clarifying how to do the temperature sensor unplugged fan test.
So with the car running, do I have to wait until it gets hot, or would I just unplug it while running at any temp?
I haven’t seen that fan spinning for quite a while now, but I haven’t really been looking at it until I had the Solus scanner to independently turn the fans on, and it didn’t spin.
 

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Unplugging the sensor at any temp will trigger both fans to run.,,,,,,,,,,,,,, assuming both work. It takes a few seconds to respond. Did you check/switch fan relays?
 

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To test knock sensor wires:
With ignition on, knock sensor plugs should have about 5 volts each.
If not, wire is broken somewhere between pcm and knock sensor connector.

Nab
 

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Discussion Starter #19
To test knock sensor wires:
With ignition on, knock sensor plugs should have about 5 volts each.
If not, wire is broken somewhere between pcm and knock sensor connector.

Nab
Thank you Nab, that’s helpful in testing the electrical part of the knock sensors.
So they use the +5 volt reference voltage going into the PCM as their source voltage.
I appreciate the information very much.
I don’t like the idea that if I were to ever be driving in a hard rain where roads were being flooded, my car could die due to old plugs with the waterproof rubber worn out.
Or driving through puddles.
I should be able to degrease and wash my engine once in a while but Noooooo....
Not with an optispark ignition system, and a bunch of plugs with the waterproofing seals worn or gone...
Anyway. I always appreciate your responses and help.
Thank you...
 

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Discussion Starter #20
96 knock sensors are different than 94-95 if you are replacing it
I am aware of that, hence they are some of the issues with going from OBD2 to OBDI conversions for easier, cheaper tuning capabilities.
But good lookin’ out BALLSS...
I appreciate the advice and information !
Thank you.
 
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