1999 STS - engine cooling fans problem - Page 4
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Page 4 of 5 FirstFirst 1 2 3 4 5 LastLast
Results 46 to 60 of 65
Cadillac Seville / Cadillac Eldorado Forum Discussion, 1999 STS - engine cooling fans problem in Past Cadillac Vehicle Discussion; He didn't say "buy" one (5-pin relay) - there are others, identical, in the fuse boxes - simply find an ...
  1. #46
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    75
    Posts
    45,947

    Re: 1999 STS - engine cooling fans problem

    He didn't say "buy" one (5-pin relay) - there are others, identical, in the fuse boxes - simply find an unused 5-pin circuit for a few moments and swap the relays for a test.

    You might consider a subscription to www.alldatadiy.com - the GM service manual plus a LOT more for your car. Cooling fan operation is discussed in detail, as well as all the electrical diagrams and troubleshooting diagnostic trees for fan operation diagnosis.

  2. #47
    palidin1029 is offline Cadillac Owners Member
    Automobile(s): 99 Seville STS
    Join Date
    Jul 2013
    Age
    64
    Posts
    34
    Thread Starter

    Re: 1999 STS - engine cooling fans problem

    FYI: My 1999 Seville STS only has 1 (one) 5-pin relay (12193602) in the two fuse boxes. I swear!!! I had stated before that, where your diagram shows three 5-pin relays in the under-hood box, mine only has one. The others are 4-pin (12193604). That is why I wrote that I would need to BUY a 5-pin.

  3. #48
    el_dorado_mex's Avatar
    el_dorado_mex is offline Cadillac Owners Fanatic
    Automobile(s): 1996 El Dorado and 1991 Cheyenne Pickup
    Join Date
    Jul 2012
    Location
    Puerto Escondido, Mexico
    Age
    36
    Posts
    106

    Re: 1999 STS - engine cooling fans problem

    Quote Originally Posted by palidin1029 View Post
    el dorado: I show 13.4 V at each fan after I remove and then replace relay2. Because I just bought the car, I am not familiar with the two sounds of the fans (low and high speeds). However, because of the voltage being 13+, I assume they are on high speed.
    Probably happening the same thing as when disconnecting ect, pcm is switching high mode (because of detecting malfuntioning relay), which we know is working (the high speed).

    your 5-pin relay is working, you checked that with verifying resistance between the fan motors and knowing that high speed works (therefore it does its job).

    you should check if any of the other relays (except cool fan 2 relay) is switched when in low speed. you do that by checking for ground at the 85 pin, means connecting test light to battery + and then connecting to 85 pin on each relay with the relay in place and the system working with one fan only.

    what we want to find out with that is where do the 12v come from at the inoperative fan...

  4. #49
    palidin1029 is offline Cadillac Owners Member
    Automobile(s): 99 Seville STS
    Join Date
    Jul 2013
    Age
    64
    Posts
    34
    Thread Starter

    Re: 1999 STS - engine cooling fans problem

    That leaves relay 1 and relay S-P to check. Will do.

  5. #50
    JimD is offline Cadillac Owners Connoisseur
    Automobile(s): '98 STS (RIP @ 206,xxx miles)
    Join Date
    Sep 2003
    Location
    Atlanta area
    Posts
    4,834

    Re: 1999 STS - engine cooling fans problem

    Quote Originally Posted by palidin1029 View Post
    FYI: My 1999 Seville STS only has 1 (one) 5-pin relay (12193602) in the two fuse boxes. I swear!!!....
    In the underhood fuse box, the relay labeled DRL is a five blade (SPDT) relay. You can safely borrow that relay as a test.

  6. #51
    palidin1029 is offline Cadillac Owners Member
    Automobile(s): 99 Seville STS
    Join Date
    Jul 2013
    Age
    64
    Posts
    34
    Thread Starter

    Re: 1999 STS - engine cooling fans problem

    Sorry...I thought it would need be the same size and number...Thanks

  7. #52
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    75
    Posts
    45,947

    Re: 1999 STS - a/c cooling fan problem

    Quote Originally Posted by palidin1029 View Post
    I had stated before that, where your diagram shows three 5-pin relays in the under-hood box, mine only has one.
    Because you did not notice that the circuit diagram from the GM service manual (posted in #2) contained the note "Wire 998 (yellow) deleted in some models", I went back - yesterday - and edited it and pins 87A out of the diagram. Now the GM diagram agrees with JimD's posted copy - the relays in question now appear as 4-pin units to someone not familiar with the running changes to the fan system in the mid-late 1990's.

  8. #53
    palidin1029 is offline Cadillac Owners Member
    Automobile(s): 99 Seville STS
    Join Date
    Jul 2013
    Age
    64
    Posts
    34
    Thread Starter

    Re: 1999 STS - engine cooling fans problem

    el dorado: I did the check on relays 1 and S-P. I had the relays to where they were almost 100% seated and used a short wire to touch pin 85 and then pushed the relays the rest of the way down. In each case, nothing happened. No change in fan operations and no light on test light.

    ----------

    Actually, to my novice eyes, the multiple 5-pin diagram is easier to understand than the other one!! Another thing I noticed was that the one diagram labels the relays as 1, 2, and 3. The other has 1, 2, and S-P.

  9. #54
    el_dorado_mex's Avatar
    el_dorado_mex is offline Cadillac Owners Fanatic
    Automobile(s): 1996 El Dorado and 1991 Cheyenne Pickup
    Join Date
    Jul 2012
    Location
    Puerto Escondido, Mexico
    Age
    36
    Posts
    106

    Re: 1999 STS - engine cooling fans problem

    testlight should have gone on at least on cool fan 2 relay, that's the one for low speed... maybe it's the method, the relays are not getting a good contact like this. is it possible for you to remove the box to get on the other side? that's where all the wires come in, and maybe you even see something wrong there...

  10. #55
    palidin1029 is offline Cadillac Owners Member
    Automobile(s): 99 Seville STS
    Join Date
    Jul 2013
    Age
    64
    Posts
    34
    Thread Starter

    Re: 1999 STS - engine cooling fans problem

    I have copied a part of your post #48 and pasted here....

    "...you should check if any of the other relays (except cool fan 2 relay) is switched when in low speed. you do that by checking for ground at the 85 pin, means connecting test light to battery + and then connecting to 85 pin on each relay with the relay in place and the system working with one fan only."

    I read this as you not needing me to test "cool fan 2 relay". I misunderstood. Will test it in morning.

  11. #56
    el_dorado_mex's Avatar
    el_dorado_mex is offline Cadillac Owners Fanatic
    Automobile(s): 1996 El Dorado and 1991 Cheyenne Pickup
    Join Date
    Jul 2012
    Location
    Puerto Escondido, Mexico
    Age
    36
    Posts
    106

    Re: 1999 STS - engine cooling fans problem

    sorry, my fault, misread what you checked. but it's a good idea to check it also, just to confirm...

    so at low speed none of the other relays gets switched, that's how it's supposed to be.

    i'm somewhat running out of ideas, everyhting is fine, except that you have 12v getting to your lh fan, where it's supposed to be less, because of the series layout. and apparently it doesn't come from cool fan 1 relay. that leaves us actually again with the motor...

    could you switch motors or put a known good one on your rh fan? or maybe just change plugs from one to the other, using some cables?

  12. #57
    palidin1029 is offline Cadillac Owners Member
    Automobile(s): 99 Seville STS
    Join Date
    Jul 2013
    Age
    64
    Posts
    34
    Thread Starter

    Re: 1999 STS - engine cooling fans problem

    I retested pin 85 on all three and no change. FYI: I did use the same method on pin 87 on the S-P relay and the light lit up...so the method appears to work.

    I did unlatch the box and as best I could, I looked under it but did not notice any loose or scarred wires nor any corrosion.

    Unless you el dorado or anyone else has any other ideas, I guess I'm to the point of having to take it to the shop.

  13. #58
    palidin1029 is offline Cadillac Owners Member
    Automobile(s): 99 Seville STS
    Join Date
    Jul 2013
    Age
    64
    Posts
    34
    Thread Starter

    Re: 1999 STS - engine cooling fans problem

    One last try to fix this...if anyone else has any thoughts, I would certainly appreciate it.

    Problem: In ac mode, RH cooling fan not working while LH cooling fan is in FAST speed. The RH DOES work when ECT is unplugged.

    In ac mode, voltmeter at RH fan shows 14.1V going in and 14.1V going out, so whatever is responsible for allowing the voltage to drop to half at the RH fan for serial mode is not functioning properly. The LH fan shows 14.1V going in and 0 out. I tested all of the cooling relays and also swapped out all 3 relays one at a time and it didn't make any difference. I did a continuity check between the cooling fans. I visually inspected the fuse box wiring as best I could and saw no loose or scarred wires nor any signs of corrosion.

    At this point, my best guess is something with the PCM not sending the appropriate signal for reducing the voltage. Any thoughts? Thanks.

  14. #59
    JimD is offline Cadillac Owners Connoisseur
    Automobile(s): '98 STS (RIP @ 206,xxx miles)
    Join Date
    Sep 2003
    Location
    Atlanta area
    Posts
    4,834

    Re: 1999 STS - engine cooling fans problem

    Quote Originally Posted by palidin1029 View Post
    One last try to fix this...if anyone else has any thoughts, I would certainly appreciate it.

    Problem: In ac mode, RH cooling fan not working while LH cooling fan is in FAST speed. The RH DOES work when ECT is unplugged.
    Please confirm you are saying LH versus RH when looking at the fans from the engine side of the radiator (or the driver's position).

    In ac mode, voltmeter at RH fan shows 14.1V going in and 14.1V going out, so whatever is responsible for allowing the voltage to drop to half at the RH fan for serial mode is not functioning properly.
    The relay labeled Cool Fan S/P is responsible for switching from SERIES mode (low speed) to PARALLEL mode (high speed). And the PCM logic determines the state of all three relays.

    Two possibilities. First is the Cool Fan S/P relay contacts are welded in the de-energized position (low speed).
    Second is the PCM is producing conflicting ground signals for the relay coils.

    The LH fan shows 14.1V going in and 0 out. I tested all of the cooling relays and also swapped out all 3 relays one at a time and it didn't make any difference. I did a continuity check between the cooling fans. I visually inspected the fuse box wiring as best I could and saw no loose or scarred wires nor any signs of corrosion.

    At this point, my best guess is something with the PCM not sending the appropriate signal for reducing the voltage. Any thoughts? Thanks.
    There is a way to jumper in several meters to provide a visual display of when the PCM is calling for fans OFF, fans SLOW, or fans HIGH. But the technique is not something I am willing to try to detail in writing.
    Having a Cadillac service department diagnose the issue with the appropriate test equipment might be $$ well invested.

    Module failure is rare and I would be very reluctant to point at the PCM without more testing. Keep in mind it might be as simple as a failed/failing ECT sensor which is confusing the PCM which in turn is confused about which relays should be energized and when.

    Bon chance.

  15. #60
    palidin1029 is offline Cadillac Owners Member
    Automobile(s): 99 Seville STS
    Join Date
    Jul 2013
    Age
    64
    Posts
    34
    Thread Starter

    Re: 1999 STS - engine cooling fans problem

    RH being the passenger side. Did a test swap for the S-P relay. No difference.

    May try replacing ECT.

    merci

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting