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Back from some testing. If I remove the LKM, F5 does not hold -- still blows. F5 only blows when the light switch is on.
Before I got under the dash to check X15 and X251 I checked continuity w/ my multimeter, and the front passenger (right) parking light had continuity; however, the rear passenger parking light did not have continuity, indicating it's shorting to ground. The bulb housing for it looks fine and I do not see any obvious rubbing/exposed wire. I plan to unbolt the tail light tomorrow to follow the wire further back. Any other thoughts on where to check first to find where it might have failed? I'm admittedly not great with electronics - does it sound like I'm going down the right path? Thank you!
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So, I'm really at a loss now. I checked continuity with my multimeter at pins 8, 10, and 30 at the LKM. All appeared to be good (between 3.1 and 4ohm-ish resistance IIRC). I checked the under hood light socket and wiring, cleaned the hood light switch. I opened up the parking/low beam light switch and all appeared to be OK inside (no burned contacts).
I checked the front and rear parking lights, and they do not appear to be shorted at the connections, at least. When I said earlier that the right rear parking light had no continuity, I believe I misspoke. The ground shows continuity, but it would appear that positive terminal for the rear parking lights on both sides do not register continuity with my multimeter, and the one on the left does indeed still work. (again, I don't claim to be incredibly savvy re: electronics) Checking at pin 8 at the LKM gives me confidence that this connection is OK.
The seat memory module does not appear to be a problem - mirror tilts down when in reverse with lights on. I also checked the dimmer switch.
Not sure what else to do at this point... I wouldn't be too rushed if my other old bimmer wasn't out of commission getting some body work done, but driving without right side markers or license plate lights at night will not be a great idea for me. I still can't help but think it odd that this issue popped up the morning after I switched out the low beam bulb on the driver (left) side, but I can't see how I would have disturbed anything relevant to shorting on fuse #5.
Any thoughts on what to check from here appreciated!
shade tree mechanic
Moderator
if it started after you switched the low beam bulb on driver side, check in that area. I do not know exactly how that looks on the US headlights, on my EURO spec headlights there is on the back of the headlights a black plastic cap where the plug goes in, inside that plug are 2 soldered wires with pin connectors, I once found these 2 wires blank without any insulation and that caused the fuse to blow. Here a pic of such cover with the wires https://www.ecstuning.com/b-genuine-...e/63121378333/
Shogun tricks and tips for the E32 series are HERE!
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Headlight terminals are isolated and insulated and appear to be good. Did a thorough check of the driver side area around the low beam (and everywhere else really). No luck so far :-/
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Continuity is a bad thing if it feeds a short circuit!
I would re-check the E20 Underhood Light circuit shown on Page 6314-03. It is one of the few F5 loads that are switched by the Light Switch, but are not fed via the LKM. If the thick Gray/Blk wire is shorted to GND somewhere, F5 will blow. (Connectors X104 and X786 are mysterious - they are not shown in any listing in sections 7000 or 8500. )
Disconnecting connector X15 will cut this circuit path.
Last edited by E32FAN; 01-30-2020 at 05:16 PM.
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Go it! Thanks, E32FAN. I'm not the brightest in the electrical dept (pun intended). If not using a sealed beam tester as mentioned earlier, what should I be measuring at pins 8, 10, and 30 on x12 with a multi-meter? I get now that they all showed continuity (really, showed between 3 and 4ohms, but that this could simply mean that they're technically continual, terminating to a short!
Was about to disconnect x15 the other night but was having trouble figuring how exactly to disconnect it. I'll take another hard look at it tomorrow, but tips appreciated if you can remember how that one disconnects.
RE: the under hood light, ground at the hood switch appears good, and ground side of the bulb socket is good. Hot side of the bulb socket has continuity when the hood switch is pressed. I imagine next step would be to check the circuit at pin 8 of X15 then? Similar to question above regarding pins 8, 10, and 30 for x12, what should I be checking for with a multi-meter? Thanks for your patience and help!
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X15 easily separates when you pry the end lever out 3/4". This operates a ramp that pushes the contacts apart.
When you short your ohmmeter probes together, you will see some resistance (one or two ohms?) and this must be subtracted to get the true resistance reading.
"If I remove the LKM, F5 does not hold -- still blows. F5 only blows when the light switch is on."
Since F5 blows when the LKM is removed, the short cannot be at X12 pins 8, 10, or 30.
When you have X15 separated, measure the resistance from X15 pin 8 to GND. If this is 1 ohm then your search is narrowed way down!
Of course there are two pin 8's - a pin and a socket. You want the wire that heads off through the firewall, not the wire that goes up to the light switch.
Last edited by E32FAN; 01-31-2020 at 12:35 PM.
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So, after some time away doing other things, I made it back into the garage. I checked resistance on pin 8 (male side of the connection, which appears to be the one I'm after), and resistance is 7 ohm. Subtracting for the multimeter's 0.1 ohm when the meter's probes are shorted together, that makes it 6.9 ohm as a true reading at pin 8. Is this normal or something to look into further?
Last edited by schnell944; 03-31-2020 at 11:11 PM.
Member
Any thoughts on this one? Since disconnecting X15 stops the short when I turn the lights on, the only next approach I’m thinking of is removing each x15 pin one by one and testing. Anyone know what the right pin extractor tool size would be for the male side?
I’m also tracking down wiring I found for a radar detector. Who knows how that was wired back in the day!
Last edited by schnell944; 04-06-2020 at 10:56 PM.
shade tree mechanic
Moderator
Here is some info on how to remove pins from different plugs and pinout tools http://www.e38.org/breakoutboxesandconenctors.pdf Breakout Boxes and Connectors
For circular connectors I made a tool DIY from a telescope antenna, works quite well. Cut the antenna where the size fits, for example for a 2.5mm pin, with that you push the cut antenna over the pin to squeeze the holding hooks and then push the next part of the telescope antenna to push the pin out. Here some pics https://www.bimmerforums.com/forum/s...flow-connector
Shogun tricks and tips for the E32 series are HERE!
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Thanks, shogun. Very helpful! I traced the wiring for the radar detector. The system looks like it's been there a while. It's wired into the blank headlight washer relay N6 (green wire in picture below) and seemingly into the bottom of the AC relay plug K33 (orange wire). I'm hopeful that when I remove all this wiring that my problem will be solved (though I thought that the last few times,). Fuse 5 is also for the headlight washers. Either way, it should be removed since the detector hasn't worked since I purchased the car, and this wiring does not seem to be great.
**update** removed all the wiring for the old radar detector, and, unfortunately, it was not the cause of the short. Will keep trying to figure this one out.
image0.jpg
Last edited by schnell944; 04-08-2020 at 10:30 PM.
Member
I would connect X16 and disconnect X15, then see if F5 holds with the light switch on. This will narrow the search.Originally Posted by schnell944
Thanks, shogun. Very helpful! I traced the wiring for the radar detector. The system looks like it's been there a while. It's wired into the blank headlight washer relay N6 (green wire in picture below) and seemingly into the bottom of the AC relay plug K33 (orange wire). I'm hopeful that when I remove all this wiring that my problem will be solved (though I thought that the last few times,
**update** removed all the wiring for the old radar detector, and, unfortunately, it was not the cause of the short. Will keep trying to figure this one out.
image0.jpg
Member
The fuse holds when x15 is disconnected and the light switch is on, suggesting it’s something downstream of that. I haven’t touched x16 yet. Did you mean disconnect x16 and see if the fuse still holds with the light switch on? That one appears to be behind the instrument cluster.
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Sorry, my error - I confused the X16 connector number.
You measured X15 Pin 8 to the underhood light and found a normal resistance 7 ohms (drawing just 1.7 amps).
Next, I would measure the load resistance of X15 Pin7, which feeds the right side marker light, right rear side marker light, right rear parking light, and right front park light. Lots of candidates here! You might measure 1 ohm to chassis ground.
Next, X251 (also beside the hood release) - you could open it to isolate several interior lamp loads. Does F5 hold with X15 connected, light switch on, and X251 disconnected?
Last edited by E32FAN; 04-09-2020 at 02:10 PM.
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Thank you, E32FAN. Pin 7 on X15 has a resistance of 78 ohms. When re-connecting X15 and disconnecting X251 and turning on the light switch, fuse 5 does not/not hold.
**addition** One curious thing (to me, anyway) is that when I open the trunk with the park/headlights switched on, the resistance measured on the hot side of the fuse #5 terminal goes from .3 ohms to 12 ohms. The trunk light still works, but if I depress the switch for the light (to turn it off), resistance at the hot end of fuse 5 goes back down from 12 ohms to .3 ohms (fuse 5 is still shorted out, mind you). If I disconnect the trunk light switch, it also goes down to .3 ohms. If I connect the trunk switch but disconnect the trunk light, resistance at fuse 5 goes down to 6 ohms. If I disconnect the connection for all the wires going to the trunk (license plate lights, trunk light), resistance at fuse 5 goes down to .3 ohms. No visible wear on any of these wires - not sure what this means/whether it's relevant...
Last edited by schnell944; 04-09-2020 at 11:26 PM.
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The trunk lid switch (Page 6320-02) circuit is fed by F33, and it has no path to F5.
So I think your ohmmeter is being confused by some voltages on the wires.
I would wire a headlamp bulb across the F5 contacts (instead of a fuse), so the bulb burns bright when the short is present. Then your detective work would be conclusive.
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Right you are, which is why I was as confused as my multimeter. Absent a sealed beam right now, I’ve been using the ground leg trick with the multimeter measuring continuity to ground on the output side of fuse 5 (not using a fuse every time to confirm presence of a short). With the light switch on, I get an audible tone from the multimeter noting a short and have been disconnecting components, moving wires until the tone stops, indicating elimination of the short - basically the same principle as the sealed beam test, as I understand it.
Does 78 ohms on pin 7 of x15 make sense? Since it’s not low resistance, that would seem to indicate there isn’t a problem with the components in that pin, right? Any thoughts on where to check next? THANK YOU!
Member
78 ohms would be just the relay coil of the K7 Parking Light Monitor Relay, so your Right Side Marker Lights are out.
My multimeters stop beeping anywhere above 20 ohms to 70 ohms, so this may be too sensitive to find a short.
You could disconnect the battery ground cable so there can be no voltages to confuse your ohmmeter.
Connect ohmmeter Black lead to the chassis (the hood latch bracket is convenient), and Red to the load side of F5. What is the resistance with the light switch on? Anything under 1.2 ohms can blow the 10A fuse, so normal might be 3 ohms, say. Then start shedding loads until the resistance rises to a reasonable value.
You can print page 6300-00 etc. to see the X15 pin numbers.
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The resistance is about 0.4 ohms on the hot side of fuse five with the negative battery cable disconnected and the light switch on.
I think I narrowed down the problem -- I pulled the instrument cluster away from the dash and saw resistance jump to between upper 2s and 4 ohms. Disconnecting the cluster light wiring connection to the cluster didn't consistently improve results. After some wiggling of wires in the area, it seems the problem is in the dimmer switch wiring or the wiring going to the light switch itself. Resistance is back down to .4 ohms and is no longer changing as I wiggle the wires in that area, but I noticed that the dimmer switch wiring has been messed with:
--Only one wire goes to the dimmer switch (the black/brown wire that goes to ground). Instead of being connected to the dimmer switch, the grey/black wire that comes from the light switch to the dimmer switch is directly connected to the grey/red wire, which goes to all the other interior lights that that dimmer switch is supposed to dim (pgs 6300-00 and 6300-01). Looks like an earlier problem was "fixed" by the previous owner.
--I guess the way it's been wired (gr/red into gr/black) effectively bypasses the dimmer switch? Perhaps the splice there is bad, so I'll take it apart and put it back together. Can't help but wonder if there's another problem elsewhere in wiring that this was meant to bypass.
I have all (or at least most) the records for the car since new, so I took a look at the big binder with fresh eyes. A "dash light out" problem has been fixed a couple times, with the dimmer switch being replaced twice. There was a "lack of resolution" to the dash lights only being out by a shop in 2016 after replacing the transmission switch and dimmer switch. "Pinched wiring in the dash" was fixed and the dimmer switch was replaced in 2014 to fix "intermittent dash lights."
Last edited by schnell944; 04-13-2020 at 11:55 PM.
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Well done - the thrill of the chase!
After you open the GR/BLK to GR/RED splice, what is the resistance of the GR/RED wire to chassis ground? Is it 0.4 ohms? This wire feeds 9 lamp loads (6300-01 & -02) and the short could be at any one of these. The radio is a likely suspect, if it has been changed.
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Thanks! Success (I think)!...with perhaps a slightly embarrassing resolution. Bottom line, it's the light switch itself. After trying to replicate the fluctuation in resistance by moving the wiring, it became clear that it would only fluctuate with more violent movement and when I held the switch and moved the wires. I then took the end of a screw driver and tapped the switch itself. With the switch in the on position I saw resistance fluctuate from 0.1 ohms to 4 ohms, and even 20+ ohms. To confirm it wasn't me just moving the wiring by doing this, I disconnected the switch and measured resistance between pin 8 (power input) and pin 1 (output to some of the non-functioning components) with the switch in the on position. Resistance continued to fluctuate between 0.1 ohms and 20 + ohms. On the other hand, when measuring resistance between pin 8 and pins 3 and 4 of the switch (headlights/fog lights) I get infinite resistance (OL), which makes sense, since the switch still turns headlights on without a problem.
Early on in this quest, I had opened up the light switch and found nothing to be burned out or out of the ordinary. This fluctuating resistance condition is probably what the previous owner sought to fix several times (and over several expensive shop visits) re: an intermittent dash lights/parking lights issue, so I feel better about how much energy it took to find this one. Thanks to everyone (esp. E32FAN and shogun) who helped me figure this one out.
Next step is to re-open and try to fix the switch I've got. I’ll again use shogun’s post early in this thread about opening it up as a guide...maybe try cleaning/bending contacts? Open to thoughts. Worst case scenario, I'll buy another working switch. Thanks!
Last edited by schnell944; 04-12-2020 at 11:42 PM.
Member
You are hot on the trail - well done! Your light switch is the intermittent resistance in the path from Pin 8 to Ground. But where is that ground actually located??
If you measure the resistance from GR/BLK to ground, you will see 0.1 ohms. The light switch is only the path that the current takes. It has been abused by the over-current events, and it is tired. But it is not the root cause (it has no Ground connection).
So you have succeeded in finding the cause of the intermittent resistance to the short (the light switch) but you still need to track down the actual short location.
Your dedication inspires and assists the rest of us! This is the kind of issue that remains "unresolved" in many cars.
(It might could be the GR/BLK wire to the radio's light. Because that's where amateurs commonly work.)
Last edited by E32FAN; 04-12-2020 at 11:55 PM.
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Thanks, again, E32FAN. Today, I disconnected the splice between the GR/red and GR/black wires that was created during previous ownership to seemingly bypass the dimmer. Resistance to ground for the GR/red wire, which goes onward to all the components that the dimmer switch dims, is 0.2 ohms. After disconnecting this splice I found that fuse 5 now holds when the light switch is on and right tail light, license plate lights, right parking lights and side markers are now all operational. So, further isolation of the problem (progress!). Also fuse five output resistance to ground shot up to 6.5 ohms after disconnecting the gr/red gr/black splice, accordingly.
I then removed the aftermarket radio and found that the GR/black wire that was supposed to go to the stock radio for illumination was not connected and was taped off. The wire appears to be visually OK, and resistance to ground at that end of the wire was about 0.5 ohms. I also found that there was continuity between the radio end of the GR/black wire and the GR/red wire for the dimmer. Seems like this one might not be the culprit?
I'll move on to removing other loads related to the GR/red wire from the dimmer tomorrow (fog light switch, onboard computer, etc. -- there are a lot of them).
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If you disconnect X15 and X251, does the GR/RED resistance rise, clearing the short? This would narrow the search.
Member
Disconnecting either X15 or X251 does not result in a rise in resistance at the GR/red wire for the dimmer. From my reading of the wiring diagram, this narrows down the suspect wiring/components to the following:
- Instrument cluster (already disconnected to no result)
- Fog light switch
- E41 dash light (what is this if not the instrument cluster? - it's location/description isn't in the component list; neither is its connection, X543)
- S300 program switch (believe this is the program selector switch for the transmission?)
-OBC
-Hazard lights switch
- ASC switch (don't have ASC)
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