924Board.org

zwoodward · Joined: 07 Mar 2006 Posts: 58

My car has been draining the battery nightly and I finally figured out that the drain is coming from accessory fuse #3, which is wired to the fresh air fan resister, fresh air fan motor, and left cooling fan according to the tech section on this board, of course the stupid PO wired the radio into this also (personally I would want the radio to not stay on while the key is out of the ignition), and I think he accidentally shorted the fresh air fan so it stays on very very low. The question is Which cooling fan is the left cooling fan, is this the left fan if you are setting in the drivers seat or the left fan if you are looking at the front of your car (working on it). I know it would be a simple matter for me to turn the car on and see if my cooling fan still works with this fuse removed (thats my temporary solution till after finals) but the car is charging right now, your help is appreciated.
Thanks,
Zac
1979 924 n/a

Smoothie · Posted: Wed Apr 19, 2006 5:43 am Post subject:

Left and right are always determined as if you were in the car facing forward (or outside at the rear facing the rear of the car or in front with your butt toward the car, etc.)
It's just like with yourself...for right side you stand there looking straight ahead and your right arm is to the right, you don't swivel your head around like in Poltergeist and say that was your left arm, right? Cars are the same, they're just like people.

_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

zwoodward · Joined: 07 Mar 2006 Posts: 58

Ok this brings me to a related question. I have removed the stereo and its associated wiring. and pretty much narrowed down my current draw to the Fan relay. What is this relay used for? I looked in the wiring diagram and the cooling fans show that they are run to a relay but the fresh air fan does not. I unplug the relay and my current draw disappears. The car seems to run fine without the relay and the cooling fan turns on and off as appropriate. Are the relays easy to come by?
Thanks,
Zac
1979 924 n/a

zwoodward · Joined: 07 Mar 2006 Posts: 58

I would like to add that after taking the car for a drive without the relay that it heats way up, to the 3/4 tick mark (right before the red) very quickly, previously it would have to set a while in traffic to get even to the half way tick mark. And so to answer my own question, putting the relay back in makes the fan way more powerful. Maybe that will help someone in the future.
Zac

Smoothie · Posted: Wed Apr 19, 2006 8:57 am Post subject:

Oh good, a man with a schematic. Kind of like a man with a plan...only different.
Pg. 258 of the Haynes, right?
The right side of the fan relay (connections 85 and 86) is the relays' coil (the electromagnet that when powered, pulls the switch closed) - follow that up and you see it gets power from the "x" circuit, so for that part of the relay to be your current draw, there'd have to be something wrong with the ignition switch ("x" supplies power only with the key turned to ignition-on, unless something's wrong with the switch).
The left side of the relay is the switch (pins 30 and 87). Follow that up and you see power comes through a fuse, an "H" terminal on back of the fuse-relay board, and ultimately the "30" circuit ("30" is always 12V+, with or without key). Come back down, follow the red wire to the left and it comes to a resistor, then beyond that you see it's a green/yellow wire, then from relay pin 87 down, it's a red/yellow wire, continue down and you meet the fan motor, then the temperature switch in the radiator. The circuit that was just traced from "30" down through the resistor runs the fan at low speed any time the radiator temp switch clicks on. For that to be your current draw, the temp switch would have to be faulty, plus you'd hear the rad fan running at low speed constantly, even long after the engine is cool.
The relay as you might have noticed by now, supplies a full 12v+ to the fan to run it at full speed by bypassing the resistor. -This full speed mode is only supposed to happen while the ignition is switched on and the engine is hot (temp switch closed).

To test the relay out of circuit, connect an ohm-meter across 30-87 and supply 12v across 85-86 (12V+ at 85, ground 86). If the relay's good, you'll get a zero reading on the ohm-meter (meaning switch is closed) when 12V is applied across 85-86 -and infinite resistance (meaning switch is opened) when 12V is removed.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

zwoodward · Joined: 07 Mar 2006 Posts: 58

Thanks a lot for your help, I'm really new to reading wiring diagrams and its a learn as you go proposition. I don't have a way to apply 12 v to the relay right now, but it is showing infinite resistance across 30-87. So I removed the connector from the ignition switch (that should demonstrate any ignition switch problem correct?) and it still draws current with the relay in but I can hear the relay open, so I know that the switch is closed until 12v is applied. So does this mean that 30 and X are crossed somewhere?
Thanks,
Zac
1979 924 n/a
PS: do all old cars have wiring gremlins?

Smoothie · Posted: Wed Apr 19, 2006 8:18 pm Post subject:

Ok, I'm getting the impression that you have the terms "switch opened" and "switch closed" reversed.
switch closed = on, current flows through, contacts are together
switch opened = off, no current flow, contacts are seperated
Without 12V, the switch in the relay should be open (infinite resistance)(this type of switch is referred to as "normally open" or "NO", switch open while "at rest" with no voltage (the opposite type of switch would be "normally closed" or "NC")).
Anyway, the statement "so I know that the switch is closed until 12v is applied" is backwards - the switch should be open until 12V is applied.

It can be tough to guess which relay is clicking with them all so close together... To be sure of what the fan relay's doing, bypass the temperature switch (connect its' 2 leads together) - this should give you resisted voltage and run the rad fan at low speed with ignition switched off, and high speed rad fan with ignition switched on.

-But yes, "30" and "x" could be crossed somewhere. If this is the case, you'd find the rad fan running at high speed during the after-shutdown cooling period, followed by the lower current draw of just the relays' electromagnet being constantly energized after the engine's cooled and the rad temp switch opens (shuts off).
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

zwoodward · Joined: 07 Mar 2006 Posts: 58

Yes, sorry I mixed them up, it was late. I just noticed that my #2 (fan relay) ad #3 (fuel pump?) relays are identical, same parts numbers (898340) and all, is this supposed to be (don't look like it in the schematic)? Now the weird thing is, when I put the #3 relay where the #2 relay is I get no current draw, but when I put the #2 relay where the #3 relay is I get a the current draw again (just on the fuel pump circuit). This makes me think is the relay again, but the relay still tests out alright.
Zac
79 924 n/a

Smoothie · Posted: Thu Apr 20, 2006 1:55 am Post subject:

That's not making sense - if you have two of the same relay and get different results by swapping them, at least one of them has to be messed-up.
The number "898340" isn't helping..does it have a 9 to 11 digit number on it somewhere? The fan relay should be something like "141 951 253B", "477 959 143" or "944 615 113 00" with pins numbered 85, 86, 87, 30 plus possibly A and B.

The fuel pump relay is a specialized part. There should be only one relay on the board with it's part number. Yours should be "433 906 059". It's there to provide a safety feature - to shut off the fuel pumps when the engine isn't running. This is to ensure that in case of an accident, you're not left upside-down in a ditch with fuel lines possibly split open and the pump/s continuing to spray fuel all over the place at 100psi.
The pins on the correct '79 fp relay should be 1, 31, 15, 30 and 87. Pin #1 takes the pulsed ignition signals from the coil and keeps the relay switched on based on those pulses occuring.

Here's some good JB info on the relays - http://users.adelphia.net/~johnbrown3/parts10.htm
[JB -If you're watching - That relay "321 941 583" you have listed and were wondering where it came from...PelicanParts shows it as being superceeded to "111 941 583", and that's allegedly a "914 headlight relay".]
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

zwoodward · Joined: 07 Mar 2006 Posts: 58

no they have no really long part number on them alltey say is 898340, made in germany, 12v 2x25A, and on another side they say 17.01.02, They are both identical wioth 30, 85,86,87, A, and B connections although they are definitly wired different at the relay. Looks like based on the wiring diagram o them There are two solenoid operated switches (30-87 and B-A) with 85-86 connected into the B-A switch as possibly a resistor circuit (theres just a blank square on that part of the diagram).

Smoothie · Posted: Thu Apr 20, 2006 2:45 am Post subject:

Those are apparently rad fan relays. "2x25A" means there are 2 switches, capable of handling 25 amps each. "17.01.02" means manufactured January 17, 2002. A square or [usually] rectangle with a diagonal line in it indicates the electromagnetic coil in the relay. I don't know what a completely blank square is for.
Anyway, if one of them is in your fuel pump relay spot, that's unsafe - need to get a real fp relay.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

zwoodward · Joined: 07 Mar 2006 Posts: 58

Is it possible that the faulty one has an internal short somewhere?
Zac

Smoothie · Posted: Thu Apr 20, 2006 4:39 am Post subject:

An internal short would mean the switch is closed all the time and you'd have full speed rad fan/s during the after-shutdown cooling period. In this case, the current drain would stop when the cooling period ends because the rad temp switch cuts the power.
For there to be a constant current drain even beyond the after-shutdown cooling period, you'd have to have something like an ignition switch or crossed-wiring problem that's sending 12V through 85-86 all the time - just do a voltage test across 85-86 on the fuse-relay board (with the key removed from the ignition switch) to rule this in/out.
Another cause of constant drain, is if the rad temp switch is stuck closed - then you'd have the rad fans running constantly at low speed beyond the after-shutdown cooling as I mentioned before.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

zwoodward · Joined: 07 Mar 2006 Posts: 58

Ok now I'm getting really confused, Haynes pg268 shows the air conditioner relay and the cooling fan rely (for nippondenso a/c cars) to be the same relay. Cooling fan is relay 2, a/c is relay 6, in between them is relay 3 for the fuel pump. Instead of being like this I have 2 fan relays for the #2 and #3 and on relay #6 I have some funky relay a Tyco VF4-45F11 12v 40/30A. It gets power from ignition to solenoid via 85-86 which switches a circuit from 30-87A to 30-87. On a different side of it there is a number 010423B. I think this is a fresh air blower interlock but this isnt listed as being a normal relay for a 1979 924 n/a.
Zac

zwoodward · Joined: 07 Mar 2006 Posts: 58

Seeing as how I got nowhere but confused yesterday I'm starting back at the beginning. My ignition switch tests fine with power to X, 15, and 50 only when the switch is on. At the fan relay I show no power to 85-86 circuit unless the ignition is on. My fan operates properly at low speed when the car is hot and the ignition is off and does not stay on all the time. When the ignition is on my fan kicks up to hgh speed like it should. Previously I have noticed the fan staying on high speed after ignition shut off but that is not currently happening, however my battery is still draining. I can remove Fuse 3 on the additional fuse board or I can remove the Fan relay to prevent the battery drain. My car has the nippondenso A/C so the wiring diagram on pg 268 applies. So none of this makes any sense to me since all I am doing Is removing 30 from the fan circuit, which shouldn't make any difference after cool down since my temp switch works fine and I know my fans aren't running all the time. Any help is much appreciated.
Zac
1979 924 n/a