I am attempting to diagnose a fairly insidious electrical issue in a 2001 Honda Prelude SH.

My question is: With the ignition off and the headlights off, but the hazard switch on, what should the behavior of the front side marker lights be? Should they be off, solid, or flashing with the hazards?

In my case I have the left side on solid and the right side off, unless I also turn on the parking lights, in which case the left side flashes and the right side turns on solid. So, I'm not really sure what's supposed to be happening.

I suspect they should be off; I'm looking at electrical diagrams and the marker lights don't seem to be connected to the flasher relay, and off seems to make more sense to me than on.

I'm hoping somebody with this car could observe. I suspect 97-01 will have similar behavior.

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    You're right, the marker lights should be off when the hazard switch is pressed. Do the rear marker lights go on as well? – Ben Feb 22 '16 at 22:30
  • @Ben Great, thanks. It looks like the rear markers behave identically to the front right. The rear and right seem fine, it looks like the problem is isolated to the front left. The demons have possessed the FL signal, marker light, parking light, low beam, flasher relay, and dash signal indicator. So knowing the right side is OK (marker on when parking lights on, off when lights off), I think I am narrowing it down to a grounding point in the engine compartment that all these share in common. – Jason C Feb 22 '16 at 22:37
  • (With left turn signal switch on: FL signal always off, marker + parking light flash instead of signal and at 2x speed, low beam line flashes negative voltage, dash indicator is 2x speed; hazards show similar issue in front left except at normal speed instead of 2x; turning on headlights w/ signal or hazards causes FL marker and parking light to flash inverted wrt dash indicator -- it's all pretty weird). – Jason C Feb 22 '16 at 22:42
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    I'd suggest checking that everything is plugged in at the proper place, I know sometimes Honda connectors can be similar. If you unplug all the connectors in the LF and plug in just the side marker can you replicate the flashing side marker? There's also a connector in the left kick panel that supplies power from the multiplex unit. This holds a few ground wires as well. – Ben Feb 22 '16 at 22:49
  • @Ben Thanks. I'll check the kick panel too; it's on the diagrams. The problem actually comes and goes (tends to not happen when you're trying to find it), it also changed form about a week ago (signal when headlights on used to be slow and irregular with dash lights stuck half on). It's also not related to water, temperature, or motion. I'm almost positive it's a poor connection / short somewhere; but I'll double check all the connectors too. – Jason C Feb 22 '16 at 22:54

As Ben mentioned in a comment, and after further experiments and closer looks at the wiring diagrams, I have found that, for this car:

  • The markers should be on solid when the parking lights or headlights are switched on at the steering wheel (including when the ignition is off).
  • The markers should be off in all other cases, regardless of turn signals or hazards.
  • They should never flash.

This sounds like a classic case of a poor connection at a grounding point - as you note in the comments, almost certainly a shared one between the various left-hand lights. Take it off, clean all the surfaces and reassemble and that ought to clear it - it's probably worth cleaning the other connections to the lights as well.

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    Thanks. I'm sure you're right. There is a point exclusively shared by all the involved components. I took a quick look, it's a mess of splices and crimps leftover from repairs to old damage. I'm just going to rip that whole section of wiring out and redo it with some nice connectors. BTW my conscience won't let me check the answer box, since this wasn't my original posted question even though it evolved in comments, and I don't want to be that question-changer guy. Hope you don't mind. – Jason C Feb 24 '16 at 0:36
  • There's a minimum time that has to pass before you can check your own answer. 48 hours or something. – Jason C Feb 24 '16 at 11:09
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    Just some closure in case anybody cares; the problem wasn't at the ground point itself. I got frustrated and gave up and took it to a shop. We found some wiring in the harness near the door that had somehow shorted and melted into a big mess (it was just behind the wheel on the harness labelled 5 here; I had been focused around the point labelled 13). – Jason C Mar 5 '16 at 6:17

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