308: DASH LIGHTS AND COOLING FANS | FerrariChat

308: DASH LIGHTS AND COOLING FANS

Discussion in 'Technical Q&A' started by thecarreaper, Nov 24, 2004.

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  1. thecarreaper

    thecarreaper F1 World Champ
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    Sep 30, 2003
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    Ok i searched the archives, but i thought i would add this here with some pics. my dash lights were not working and the fuse was blown. turns out the white wire for the rheostat was loose and must have found a ground and blown the fuse. first i plugged in the white wire, replaced the fuse and checked the lights. the dash lights were very dim and pretty much useless. the 3 local parts stores i went to only had one pack of two bulbs. the Sylvania 3893's are the large bulbs and you need a bunch of them. the Sylvania 2723's are the small ones. when i can find a quanity of 3893's i will replace all of them.

    the pics will show the rheostat for the dash lights. Mr Dave Handa had a post in the archives that was extremely helpful. the link tells you to make a small jumper wire with male ends to join with the female ends on the white wire and the doulble yellow wires. this trick worked like a charm and the lights are now useable. the new Sylvania bulbs are supposed to make things even brighter. Mike328 was kind enough to have already done this modification on the 308 i later bought from him. i can say that the combination of new bulbs and the jumper wire make a great deal of difference. i did not have to remove my steering wheel to get the gauge cluster top off, but it was NOT fun and i work on aircraft all day. small hands with long fingers REALLY help.


    Cooling Fans. i obtained a switch for a 1979 vw Rabbit pn 405012 sku5970660 from Advance Auto parts. parts was $12.29 and fit perfect. someone has added 308QV fans to my 77 GTB already, and there is a toggle switch as a backup in case you REALLY need to turn the fans on early.


    now i need to figure out how to get the door pin switches for the interior lights to work properly. i hope in some small way this helps some folks. its dark , raining and getting late, yet i was still able to do all this stuff in the garage, thanks to the info here in the archives.
     
  2. thecarreaper

    thecarreaper F1 World Champ
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  3. thecarreaper

    thecarreaper F1 World Champ
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  4. f355spider

    f355spider F1 World Champ
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    May 29, 2001
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    I just do the speedo and tach (not all the instruments)...the odd thing is the tach invariably ends up not quite as bright as the speedo. I think it has to do with the substitute bulbs for the tach not being as bright as the replacements for the speedo...but in searching cross referrence charts, that was as good as it gets. Just doing the reostat bypass, seems to make the biggest difference though. The combination of the two makes them much more legible.
     
  5. thecarreaper

    thecarreaper F1 World Champ
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    yes! the carw as not safe tod rive the way it was. at least now i can see the dash lights...... next trick will be the headlight upgrade!! :)
     
  6. Jdubbya

    Jdubbya The $10 Trillion Man
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    It's like deja-vu all over again!! I've spent the last year sorting through all this on mine too!
     
  7. thecarreaper

    thecarreaper F1 World Champ
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    the right cooling fan comes one, but the left one does not. the left one works if power applied directly and the switch and factory wiring are bypassed. more fun with wires!
     
  8. Steve King

    Steve King F1 Rookie

    Feb 15, 2001
    4,367
    NY
    I would look at the fan relays as one of the problems. The right fan is on a circuit associated with the AC system and turns on when you turn on the AC. The left fan triggers from the temp. sensor in the bottom of the rad. Also if the AC is off and the water temp triggers the rad. sensor then both fans turn on. So try to jumber out the rad. temp sender to see if the left fan works. Also check the fuse panel sometimes you have a loose connection or rivit which will cause the problem.
     
  9. thecarreaper

    thecarreaper F1 World Champ
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    thank you, i was wrong, i thought the LEFT FAN was for the a/c. the a/c compressor is out for the winter, i have a small leak and i dont want to waste time on it now hunting for it. i would however, like to get the fans working properly. i installed the switch in the radiator, and i have 12v to one of the two wires going to the switch. i hope it does not matter which one goes to what termilal as they were not marked for polarity. i am assuming one wire is a 12v constant and when the thermocouple in the switch gets hot enough t closes and completes the circuit and turns on the fans. (?) correct?

    the car has QV fans and new relays. fuses are ok and there is power to the fusebox and relays. the fans will work if 12v is jumpered to them. there is a hidden toggle i found under the dash that will turn on the right fan. if i cannot get the system to work i may have to put both fans in series and run the 12v to the toggle to turn both of them on. i would rather fix it properly though!! i have disabled the toggle switcht o see if the fans come on now. now its so cool i may have to drive it for some time before they are even needed. any advice /additions to this thread would be nice, i am on vacation till monday and i am trying to get the car all sorted out.
     
  10. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
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    Michael,
    On my '77, both fans come on when the thermostatic switch in the radiator kicks on. But the right fan (passenger side) comes on regardless of operating temperature when the AC is switched on. There is a relay and a fuse for each fan. Both relays are activated by the thermostatic switch. Only the right side fan relay is operated by the AC. But if the thermostatic switch is on AND the AC is on, then the AC turning on the fan is redundant. Anyway. if the thermostatic switch switches on, BOTH fans should work. As you know, the fuseboxes in these cars are almost always responsible for electrical issues, so check that the fuses are supplying current not just to the fans themselves, but also the relays that switch the fans. The relays use a different fuse.

    What is the ON temp for that VW thermostatic switch? I would like one that kicks on a little lower in temp.

    Birdman
     
  11. thecarreaper

    thecarreaper F1 World Champ
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    the on temp is 180, there is one also that kicks on at 160, i think.

    i drove the car quite a bit today, and it never got above 190! fans never came on. the a/c compressor is in a box, so i may have to do *something* to the wiring ( green wire?) to fool the fans into coming on when the switch in the console is turned. i purchased halogen headlights today also, i will do those tomorrow. anyone want to volunteer how you make the lights stay up with the car off i would love to know ( 77 gtb) .

    the relays for the fans are new, the QV fans were just added , yet the fans wont come on, and it was hot here a week or so ago. i want to fix it right, i hate having toggle switches and funky wiring.

    Birdman, do you think i should check the switch in the console for the a/c and see if it has something to do with both fans not working??? thanks !
     
  12. Peter

    Peter F1 Veteran
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    Dec 21, 2000
    6,440
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    #12 Peter, Nov 28, 2004
    Last edited by a moderator: Sep 7, 2017
    I did the rheostat bypass for my dash lights and it worked well, but recently, I picked up a catalogue from an electronic-parts supplier and noticed they sell LED bulbs (with built-in resistor) that looks like they'll fit the gauge lights, on my GT4 at least. Neat thing is they're avaliable in an assortment of colours. LED's offer brilliant, intense light at cool temps, over incandescent bulbs. I'll investigate this further at a later date. Too many winter projects on the go for now.

    Below is the before and after pics of my dash with the 'stat bypass. I had posted this in the OLD forum, which seems to be inaccessible now (so I'll repost here):
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  13. Birdman

    Birdman F1 Veteran

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    Let it idle in the driveway for 10 minutes. The lack of flowing air through the radiator will bring the temps up enough to where the fans should be kicking on.

    I just hooked a big battery charger to the battery so it wouldn't die, and turned on the running lights. If you haven't yet done the headlight pop-up mod, the headlights pop up when the running lights are on. Just be careful that they don't go down while you're working on them. You definitely could lose a digit that way.


    I agree. The circuit is amazingly simple. The relays get 12 V to their coils from the fusebox. From there, the thermostatic switch in the radiator just closes to ground when the temp hits the right number (180?). It's just a series circuit from the fusebox to the relays (two in parallel) to the thermostatic switch to ground. If the fans work with the switch that the PO installed, he may have (stupidly) disconnected the wire to the thermostatic switch at the back of the relay panel. You can test by just pulling the two wires off the thermostatic switch and check with a voltmeter to see if you have 12 V across those wires. (One is 12 V and the other is ground. I have no idea which is which and it doesn't matter). I'm guessing you won't have 12 V there and if you pull the panel that holds the relays, you will find a lonely wire in there that used to go to the relays from the switch. BTW, you could leave the manual toggle switch AND hook up the thermostatic switch. So you end up with two parallel switches to accomplish the same thing. Sort of like a back up plan system.

    It shouldn't. The AC switch operates the right fan only via a completely seperate relay. I'm attaching a simplified schematic of the AC circuit in the car. (It shows only the components that are part of the AC and right fan circuit. It leaves out the other relay for the other fan that is also operated by the thermostatic switch). This schematic shows how the right fan motor (#25 on your OM schematic) can be operated by either relay #99 (via the AC circuit) or relay #30 via the thermostatic switch in the radiator.

    I think your problem is in the way the PO modified the circuit for the manual toggle on the radiators. I think he substituted a toggle in the dash for the thermostatic switch in the radiator, probably not realizing that as long as they are in parallel, not series, you can keep both and either one will turn on the fans.

    Report back!

    Birdman
     
  14. Birdman

    Birdman F1 Veteran

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    Peter, who is the supplier? I have been wondering why someone hasn't made LED's to replace standard bulbs. How cool would those be as reverse lights, if they could make them bright enough?
     
  15. thecarreaper

    thecarreaper F1 World Champ
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    i just read this, it was SUPER NICE here today and i DROVE THE CAR ALL DAY ! :) the car got to 195 and still no fans, so i reached in and plugged in the seperate wire for the toggle and turned the right fan on since i was in traffic off and on all day.

    to clear some things up:

    1)the fan relays are new.

    2) there is power to the fuses and one wire at the thermoswitch has 12v the other does not not .

    3) either fan will work if straight wired with a 12v source and both have good grounds.

    4) thermal switch is new should be "on" at 180F

    5) THANK YOU ! for the diagram, i bet its something in the fuse box...... i bought all 4 that NAPA had in stock to do the "glass fuse" upgrade on this car and whatever other fcar i may get ( ya never know!)

    i need to add the foam around the radiator, but now that its winter it wont be a big deal here. i just had the major done on the car and they used distilled water with antifreeze and water-wetter stuff. i will figure out these fans and get rid on the toggle switch , or reserve it as a "emergency back up"

    i am hoping to do the headlights and the parking light upgrade asap.!

    Birdman, thanks for the help ! Michael.




    edit.......i need to check to see if there is power at the relays from the fuse box....... HMMMMMMMM :)
     
  16. thecarreaper

    thecarreaper F1 World Champ
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    oh yea..... the toggle switch they added has a green wire from the battery to the toggle switch under the dash, with another green wire run only to one fan ( the right one) the previous owner said it was a temp fix since the switch for the car was ordered (i never got one with the car.) i bet since the relays are new that there is a problem with power going from the fuse box to the relays........ but i do have 12v to one of the wires with the key on at the thermo switch.
     
  17. Peter

    Peter F1 Veteran
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    Dec 21, 2000
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    Mode Electronics

    Like I said, I only saw these in the catalogue, not in the flesh, so I don't know if its the same size, but from the description and the picture, they look awfully similar. Model: T3 1/4 (?). Avaliable in bayonet and screw base styles. Again, I have to go back to the store, see if they have them on the shelf and compare to the ones in the car.

    If you go to the above link, click on "New Products", you'll see them there and it'll direct you to the page in their catalogue (pg 44 & 45).
     
  18. Jdubbya

    Jdubbya The $10 Trillion Man
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    To keep the lights up simply turn them on and then disonnect the battery. It's a good idea to always do this to work on them anyway so you don't get a finger caught. You won't regret doing the headlights either, I did mine. Pretty easy once I figured out how it all comes apart, and now I can actually see at night!!

    On the fan issue mine don't actually come on till about 190 or 195.
     
  19. thecarreaper

    thecarreaper F1 World Champ
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    thanks! my old 308 gts was more or less the same way as far as the fans go. ill work on the issues this week.
     
  20. FourCam

    FourCam Formula Junior

    May 19, 2004
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    Wow! I just did the speedo and tach in my 79 308 and didn't even need the jumper wire they are so bright now! I have avoided driving my car at night because of this and the headlight issue, but that has all changed. Thanks to everyone who added to this. Can't wait to do the headlights now...
     
  21. ronr

    ronr Formula Junior

    Oct 30, 2002
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    thecarreaper,

    I'm not seeing the photos. Did they get lost during the hard drive crash? If so, would you mind reposting them? I'm logged in, so that shouldn't be the problem.
     
  22. f355spider

    f355spider F1 World Champ
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    Good luck on the headlights...I recommend the Hellas:http://catalog.com/susq/hella/headlamp.htm

    Standard bulbs are fine...you could upgrade to the "plus 50%" which are a bit whiter in appearance. The "plus 100%" are a bit blue, I am told.

    The Hellas are great on my 328....better performing than the feeble things called headlights on my 355 (and this is called progress?)
     
  23. thecarreaper

    thecarreaper F1 World Champ
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    #23 thecarreaper, Dec 20, 2004
    Last edited by a moderator: Sep 7, 2017
  24. ronr

    ronr Formula Junior

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    Cool, Thanks!
     

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