Mike Frye

I called this post -2 because I have done many searches on this one and the closest thing I found was called 'Headlights not retracting' from 2002.

(I don't know how to put the url in here for that thread, but the thread was just 'headlights not retracting').

Anyway, that post was similar to mine except for the resolution which for him was a broken wire, mine has good wiring from the motor plug to the relay board, although the pins are different from what was listed. Here's the scoop:

Problem: Headlights go up when turned on properly. Turn off when turned off, but don't retract. I jiggled the keyswitch and light **** and don't get any change. If I manually lower them 2/3 of the way, then turn them on, they go down then pop up.

Here's what was suggested:

check continuity on these wires (should be 1 Ohm or less):

relay socket pin 30bM to pin 1 on motor
relay socket pin 56 to pin 2 on motor
relay socket pin 86M to pin 3 on motor
relay socket pin 30M to pin 4 on motor
relay socket pin 31 to ground
headlight motor case to ground.

check for DC voltage (should be more than 12VDC):

relay socket pin 30 has battery voltage
relay socket pin 30a has battery voltage
relay socket pin 30b has battery voltage

For mine, I get continuity between relay socket pin 30bm to pin 2 on motor and
from relay socket pin 56 to pin 1 on motor which is the reverse of what was listed (model year difference?).

Good news is I was able to get continuity from each of the four leads back to the relay board, so the wiring seems OK, even if it's not where it needs to be.

So I was thinking, ok, reverse the leads to pin 1 and 2 and I'm golden right? Wrong.

I think what it did (and I need to check this again, so don't count on this part) was it just didn't go up in the first place.

Part of me says get a new headlight relay and try it out, but I'd rather know that was the problem than just start part swapping. Also my budget only allows for replacing broken parts .

I won't be able to test it while I'm online tonight because I have to vote, but if anyone wants to chime in on this perennial question, please do and I'll send results of any tests you can come up with tomorrow or Thursday.

Thanks in advance for any help on this one.

SharkSkin

There are a couple of diodes where the wiring goes into the headlight motor -- check them and make sure they are OK. I think if one is bad it will affect one direction of movement. You can replace them for a buck or two.

Mike Frye

Dave,

Cool. I'll get back in there. I took the motor apart and checked to see if everything was making contact and checked the diode condition (on a PCB if the diode is blown it's easy to tell, but maybe in this case it can just go bad without looking burnt?)

I didn't meter them because they looked OK, but I do have a diode setting on my meter so I'll check them out.

Alan

Yes - what Dave says.. there is a major difference in operation pre '87 and '87-S4+

Take out the HL motor and dissassemble. Check the diodes and the track continuity (use cleaner if needed) for the switches... you can connect a meter to the switch connections and rotate the motor by hand.

Alan

Mike Frye

Sorry to bring this one back to life, but I haven't had any success.

Per Dave's advice, I opened the motor again and checked the diodes with the field wiring off. I got .555 on the diode setting of my Fluke 10 meter in one direction for each, and nothing in the other direction. I'm pretty sure this means they're both fine, what I was expecting was for one to look toasted or have a cold solder joint or test differently than the other (since up works fine).

I resoldered all of the terminals in there just to make sure it wasn't something I couldn't see and metered everything again, no change.

Should I just try replacing both diodes just to check that box off the list?

I also opened up the relay and cleaned the contacts on the three SPST relays in there and metered them (only after I cleaned them unfortunately) all read good through the contacts. I didn't see any obvious burn marks on the components on the relay board either. Cleaned relay pins and reinserted, still no change. They go up and on, but not down.

Do I have to bite the bullet and just order the headlight relay even though I'm not 100% sure that's it?

Any other suggestions would be much appreciated.
thanks.

Lizard928

I would get another 928 of same year that you can park side by side and check the placement of wires.
if the wires are 100% correct, remove the headlight switch and check its wire connections

Mike Frye

Lizard,

A good idea.

I don't know any local 'listers or even 928 owners, so probably not an option.

I can check the headlight switch, do you think that's it? I guess that's really the only moving part I haven't tried, so it's worth a shot.

I really thought someone was going to say to switch out the headlight relay and be done with it.

Fogey1

You could remove, open and inspect the headlight relay. Doesn't sound like you're scared of the VOM.

Lizard928

NJSharkfan, pm me your email address and I will snap a pic of the order of wires on an 86 (will be the same) or tell you the order manually, however I am in the DFW airport on my way home from mexico atm. So I cannot help you right now

Mike Frye

Will,
Did that and cleaned the contacts in there as well, no change, but thanks. I didn't actually meter all of the components for the correct values, but usually with a PC board like that you can see a burn mark if someone has 'let the smoke out'.

I hate to just order the relay without knowing that that's going to fix it. Never been a part swapper, although it wouldn't kill me to have the spare laying around if I don't need it. I just want to be sure I've tried everything else.

Lizard,
PM is on the way, and thanks.

SharkSkin

Is fuse #39 OK?

T_MaX

As per the 928 spl's site for a 1985-86:

Fuse no. 27 Headlamp Motor 15amp

Relay position XXIII-XXIV Combination Headlamp P/N 928.618.107.02

Do you have the wire diagram for your MY? If so, do a bench test on the relay and motor.

Also you can and should check the switch (at the fuse panel) to see if the switch is working as designed.

JM .928

SharkSkin

Whoops, thanks for the correction, T_Max. I was looking at the wiring diagram, and was in too much of a hurry. I thought the current track where fuse #39 is was tied to the HL motor, but it's not -- it's right next to it.

In the original post Mike mentions the headlights moving under their own power, so I doubt it's fuse #27.

Sorry for any confusion.

Mike, it sounds like you've been very thorough. Maybe it's time to bite the bullet as you say... One sneaky way I found of getting spare relays was to buy a CE panel from the junkyard -- had defrost, HL & other pricey relays still plugged into it -- they checked out good and the whole thing cost about what a new HL relay costs.

Mike Frye

T_Max,

I have the wiring diagrams. Do they have the internal wiring of the relays and motor? I hadn't thought to check that far. I'm pretty good with the field wiring and spotting if something is broken/corroded, but I'm not sure I'd be able to bench check the relay board just going by the wiring diagram. The motor is pretty simple and I'm pretty sure that the diodes are good, so what else could be wrong if the motor runs perfectly to put them up, just not down?

Dave,
I'll have to check around for the CE panel, that's a cool idea and it would give me the possibility of getting some other spare parts out of the deal. I guess my search continues...

SharkSkin

Mike, the wiring diagrams are very thorough. I forget who it was who recently took a CE panel from a different MY and wired it to suit their car using the diagrams and the old panel. The relay internals are shown with the major contacts, but in the case of the HL relay the electronic portion is just represented with a transistor symbol, so that part is a bit of a black box. Here's what it looks like on the 85 diagram: