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95 Caprice 9c1
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Discussion Starter #1
hello everyone, so I have a 95 9c1 and both of my cooling fans run at the same time, both fans come on a couple of seconds after start up, so pulled the relays and both are good but when I went to pull fuse I noticed PRI/FAN fuse port is a little melted, how would I go about fixing this problem I have, oh yeah it still works with it being melted, when I pulled the fuse out the PRI Fan turned off right away when I put it back in the fan turned right back on, so I really can’t figure out why both fans run all the time, I have replaced WP, sensor in WP, sensor on passenger side block, thermostat, I haven’t touched the radiator yet, can a bad radiator make both fans run
193476
 

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The PCM controls the fans so maybe you should start with getting live data out of it. You may have a broken sensor wire. You gave no information on what the dash gauge shows. Is it reading normally?

Do a search of the forum to decide how you want to get data out of the PCM. Laptop and cable or scanner are choices. A diagnostic charge from a mechanic might have been cheaper than the parts you threw at the car. Just be sure they have a OBD1 scanner.
 

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It looks like your fuse box has seen better days. Get a fuse box and swap it in. Again this has been talked about before. This current thread has a lot of info, diagrams, ect.

 

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Discussion Starter #4
@Z09B4U those parts were changed prior to the discovery of the melted fuse box, as far as the scanner I can’t find one for OB1 at all where I’m at, I live in California, LA everyone has an LS motor no one has a LT1 anymore
 

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Normally when we want to check that the fans and the PCM work we unplug the temperature sensor and the PCM defaults to fans on for safety. A broken wire would also force the fans to run, So you could unplug the temperature sender and the PCM and test the wire between them.

Again does the temperature gauge work?

The fuse box seems to work from your description but it may fail in the future.

I live in California, LA everyone has an LS motor no one has a LT1 anymore
My understanding is you have to do a emissions test. It is hard to believe only test stations have OBD1 and no one has a OBD1 for repair or pretests.

If you have a laptop, a cable and software cost about the same as a couple of hours of mechanic's fees. I agree it is hard to shop for a scanner but the California population is close to the size of my country's population. I bet someone is selling one now or pretty soon close to you. I had to shop for six months.
 

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Your fan relays should not be inside the fusebox (anymore). There is a Tech Service Bulletin that relocates the fan relays OUTside the fusebox by the wiper motor, specifically because they tend to melt in the fusebox.
Gary @ Innovative Wiring makes a fan motor & relay harness specifically to avoid this ever happening again; it improves on GM's Tech Service Bulletin and is worth every penny.

You already replaced the H2Opump temp sensor, but the wiring that leads away from the H2Opump temp sensor back to the pcm may also be compromised even if the sensor itself works.

If something's wrong with the AC pressure sensor, it might also be commanding both fans to stay on, but this is even more unlikely.

Ultimately, you need some kind of OBD1 datalogging to see if either the H2Opump temp circuit is compromised, the AC pressure sensor is misreporting, or some other sensor issue is tricking the fans into staying on constantly. Sorry.
 

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....... the wiring that leads away from the H2Opump temp sensor back to the pcm may also be compromised even if the sensor itself works..........
The wiring and connectors get more than their share of discussion about problems with that sensor.
 

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The wiring and connectors get more than their share of discussion about problems with that sensor.
Might have something to do with the fact that those wires are too thin for their own good.
 

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95 Caprice 9c1
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Discussion Starter #9
@Marky Dissod there is a single green relay that is in back of the fuse box, but outside of the fuse box I’ve been trying to figure out what that relay goes to, but I will go thru it tonight when I get home from work
 

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Discussion Starter #10
@Z09B4U yeah I’ve tried to unplug that sensor the fans are running already, no matter if I pull sensor the fans are running as soon as I start the car
 

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Discussion Starter #11
@Marky Dissod I’ve been to like a thousand shops and parts store trying to find a scan tool for this car, I can’t find anything, a friend recommended me to drive almost 100 miles to a guy he is sure can scan the car, at this point I might have to
 

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Discussion Starter #13
There is a green relay in the background of pic I posted anyone know what that relay goes to
 

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That may be GM's TSB for your 2ndary fan, which unfortunately was only implemented on 9C1 models AFTER melting inside the fusebox.

(25 years later, some people continue to insist that they do not need to perform this or that TSB because their car never had the symptom that would warrant it, whereas I needed considerable convincing in my early 20s to NOT have a preemptive appendectomy. I still wonder if I should remove my appendix, but am sure every Ironblock LT1 should disable its AIRpump.)
ANYWAY

Please forgive the following.
Disconnecting the H2Opump's coolant temp sensor makes the pcm say, "the difference between the IAT sensor and the H2Opump sensor is frakken bu11$h!t; run both fans just in case".
However there are several other things that can happen that can make the pcm run both fans just in case, but for the life of me, I cannot remember any of the other conditions that make the pcm do this, and it's been long enough that I cannot remember which forum elder would know.

Nonetheless you should find out WHICH of these specific conditions is causing your pcm to do this.
Ultimately this is why I and others resort to suggesting that you get an OBD1 scanner of some sort.

If you really wanna get your money's worth, get yourself
an OBD1 cable (I'll only endorse TunerCAT's $85 cable, you can find one for less, I hope it's as trouble free)
$EEhack (free, yet still being improved, can do lots more than just help you find out why your pcm is running both fans)
 

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Discussion Starter #15
@Marky Dissod thanks for all the info, I’m going to check the harness on ECT tomorrow morning to make sure I’m getting the proper signal, I’m going to also purchase that cable for the OB1 thanks I’ll update the outcome tomorrow morning
 

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Your fan relays should not be inside the fusebox (anymore). There is a Tech Service Bulletin that relocates the fan relays OUTside the fusebox by the wiper motor, specifically because they tend to melt in the fusebox.
Gary @ Innovative Wiring makes a fan motor & relay harness specifically to avoid this ever happening again; it improves on GM's Tech Service Bulletin and is worth every penny.

.......
Second time citing the same post :unsure:

That may be GM's TSB for your 2ndary fan, which unfortunately was only implemented on 9C1 models AFTER melting inside the fusebox.
....
Good info - thx. I eventually found tsb 53-62-04, and sure enough it's only relocating ONE of the fan relays, and only issued for 9C1 and SEO. I have never come across that TSB, but can offer that both fans have been replaced in the last 5 years from just normal bearing wear. GM concern for customers' budgets apparently called for withholding the patch from 'normal' SS/Cap/RM/OCC. :sneaky:

As usual, Gary appears to have all the refit permutations well in hand.

Trivia: Cadys come stock with both relays already outside the box.
 

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Your fan relays should not be inside the fusebox (anymore). There is a Tech Service Bulletin that relocates the fan relays OUTside the fusebox by the wiper motor, specifically because they tend to melt in the fusebox.
That may be GM's TSB for your 2ndary fan, which unfortunately was only implemented on 9C1 models AFTER melting inside the fusebox.

(25 years later, some people continue to insist that they do not need to perform this or that TSB because their car never had the symptom that would warrant it
Good info - thx. I eventually found tsb 53-62-04, and sure enough it's only relocating ONE of the fan relays, and only issued for 9C1 and SEO.

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

In the above link you will find a pdf that appears to be the GM TSB. If it is fake I apologize in advance but every reputable reference I have found reads the same way.

This TSB refers to the PRIMARY FAN RELAY only. And only for cars in sever duty situations. If you want mind boggling idle hour numbers research the difference between ford police cars (P71) and civilian cars. The number of hours a police car sits with it's PRIMARY FAN cycling is huge. Standard driving cycles do not have this issue.

I expect well respected forum members to quote GM documents correctly and not mislead people who trust what is presented on this forum.

I respect peoples opinions and experiences. This does not mean their opinions and experiences are applicable to ALL situations.

As usual, Gary appears to have all the refit permutations well in hand.
Caprice / Impala SS / Roadmaster | IW
I want to be clear that I have never found anyone say anything bad about Gary's products. I have not seen them in person but he has to put time and thought into the design and material quality.
 

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That is one helluva better rez of the TSB than the little image I found. Good you confirmed GM's official TSB applied to only one fan, and also in confirming it applied to only 9C1 and SEO. Also appreciate correcting that it (the TSB at least) applied to the primary v. secondary as previously got misstated. I'm not catching much other errant info or misdirected guidance that's been offered.

This TSB never made it to recall status even for the cop cars, and made it 25 years without me hearing about it once. The OP is making out like a bandit with all the background and direction here, and he sounds on it well enough just to closely inspect his own fusebox for signs whether to apply some or all (or with regard to Gary's kits even more than) the TSB to his own problem(s).
 

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Lets get back to the OP’s issues.

I suggested replacing the fuse box. Why fuse #7’s space is melted. The OP has made NO mention of melted relay sockets, AND reports that the relays control the fans. It might be in the OP’s interests to provide diagnostic suggestions and leave upgrades until the original problem is solved.

The melted #7 fuse area is connected to the primary fan relay coil. So replace the relay and relocate it like the TSB.

NO. The relay coil draws less than 0.5Amp and a short should have blown the fuse.

Well there is the problem the “crazy GM engineers” used a 10Amp fuse.

No. This fuse is also the power fuse for the A/C clutch coil. The melting may be the result of issues with the A/C clutch system slowly overloading the circuit or persons unknown using a larger fuse while messing with the A/C circuit.

There has been a lot of messing around in this box. Three different relays and the OP is asking about a extra relay outside the box.

Bad temperature information, malfunctioning A/C are issues that should be checked out. They are things that “fool” the PCM to run the fans.

The problem may be complex and the OP could help the forum help him by getting a FSM. Then we could refer to and discuss things without scanning, typing, and posting things that may still be covered by copyright laws.
 

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Discussion Starter #20
thanks for the info, this is why I love this site. I will be updating in a few while I have time to go fiddle with it, again thanks to everyone for valuable info and tips, update and pics coming soon ✌🏾
 
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