Auxiliary fan issue.

[grebmohr]

Ok here is a strange thing. To help you either need a car with a correctly working low and high speed fan or you need page 6450.6-03 of the trouble shooting manual.

I got the high speed fan working...fuse behind the dash was burned up.

position 30 on the High speed relay transfers to 87 when not on- this then goes to 30 on the low speed relay. this is all per the book so far.

the way I read it, 86 on the low speed relay should have voltage when the key is on. On mine, it does not. I do have voltage on 85 which seems wrong to me.

Closing pin 3 on the double temp switch should cause the normal speed fan to come on. On mine it does not. closing pin 2 on the Double temp switch Does engage the high speed fan.

So back the normal speed relay. If I were to find the reason for no voltage on 86 and correct it. then I would be putting 12 volts to both 85and 86-- Not good I should think.

Am I missing a defect or problem on the x6000 of the DME? Is my DME malfunctioning?

I'm kinda lost. When it comes to DME.

I still need to put power to both leads of the fan and make sure that both legs work correctly.

Can someone check their low speed relay points and verify that voltage is on 86 and not 85 or is it?

Any ideas? Thanks in advance.

[grebmohr]

bump-o

[xxxJohnBoyxxx]

Can you post a picture of tthe relay schematic? with that I can tell you what it should have on 85 & 86 without testing...

[Junk]

diagram is confusing me, looks like the high speed relay would have to be energized always for the fan NOT to be running at high speed..? Am I missing something or the diagrams aren't showing the relays in the right position..?

[Junk]

this diagram makes more sense to me..

[grebmohr]

High speed is a magenta relay with a 2 position output/pass thru. Theoretically, the dual switch not grounding either trigger would leave the HS relay's "always hot" connected to the normal relay #30 =always hot in. When the first stage of dual switch is grounded, the normal speed relay would be activated. When the second stage of the dual switch is grounded, the HS relay would energize thus moving the power from XX (ie lead to Normal 30) to XXa, the lead to the HS fan connector.

PHEW! all that said Mine is not following that path- my previous owner/idiot may have jacked around the leads to make it work but I'm trying to see if anyone else has any ideas.

Is everyones HS relay purple/magenta? Normal speed yellow? Same as the A/C control relay nex to it?

Power on the receptacles of the normal at key off and key on?

Thanks for our help guys, I appreaciate you looking into it for me.

[bullmand]

For whatever it's worth, the Bentley manual specifically mentions the cooling fan on cars with M44s being routed through the DME and only being fully diagnosable by a dealership. I can quote you the passage later if you'd like. I'm assuming the DME is using info from other sensors to decide when to turn the fan on, but I don't know that for certain.

[xxxJohnBoyxxx]

grebmohr, I can not read the attached pictures at all also I don't know which one is yours.

I can not understand your questions either since you seem to speak a different language then me when it comes to trouble shooting electronics.

1. Does the high speed fan come on with A/C unit?
2. When you check you Rad switch there are three pins. Are you using the center pin as your common pin and then shorting the center to either of the outside pins for fan testing? You stated high speed worked doing this but are you using center as your common?
3. You are 100% sure you have no bad fuses?
4. You are 100% sure your fan motor is good and works both low and high speed? There are separate windings and they need to be checked...OHM them or hook up a battery to them.
5. Your DME is dry and you are 100% sure there is no mold looking stuff on the curcuit board?

I ask this before we try to trouble shoot relay issues. Relays go bad and wiring can get broken but it is most likely a bad fan motor or something simple so before we go after wiring issues I would like to know if you eliminated all these items...

Also nothing bad was meant by your electronic language maybe I don't speak it right

Best, John Smith

[grebmohr]

Got it covered. Yes you are right with regard to the DME, that it is the ultimate authority as to whether the normal speed fan turns on. The high speed fan is operated through the double switch and HS relay. The high speed fan operates when jumped/shorted to the center pin. The low speed fan can be forced to run both speeds with a 12 volt power supply.

In the spirit of my original question, I wanted to double check what relay socket terminals had voltage "always hot" and "Key on",that's it.

Turns out I was right I removed the fuse block and traced the wire in question and found someone had re-pinned it incorrectly in an attempt to fix the fan which simply had a blown 40amp fuse...

Problem solved- thanks anyway. I often loose people when trouble shooting as I move quickly and use the term that is closest to my lips at the time I also assume everyone is right there with me even when they are not.... My job review stated that... :-)I may not speak the engineers language, but I very rarely miss- I'm that good.