Parasitic drain

[RawbDidIt]

I have a problem with my 97 K1500. It's pretty much in the title. I've narrowed down the drain to circuit 9 marked as "Park Lps" it's a 20A fuse. From what I can tell it's a brown wire that goes to all turn signals front and rear, and the marker lights on the front corners, as well as the license plate lights. Here's the steps I've taken so far:
1. Connect multimeter to ground lead and negative terminal of battery with key in off position. Truck off for over 30 minutes. Current reading: 250-300 mA
2. Disconnect fuses until current drops below 50 mA: circuit 9 fuse pulled current reading at <20mA
3. Disconnect all loads on circuit one at a time. Reading remains at 250-300mA with all bulbs removed.
4. As a last resort I replaced the main headlight switch. No effect, current reading still 250-300 mA
5. Realized the trailer lights are after market and not listed on the wiring diagram, removed harness at splice. No effect.

I'm out of ideas. Short of running new wires for the entire circuit, I don't know what to try next. I've looked over the wiring run that goes along the driver's side frame rails, the sheath is still intact, no signs of pinching, rubbing, etc. Is there a way of testing the light sockets without cutting the wires? Did I overlook something simple? For good measure I also checked the third brake light cluster on the top of the cab for good measure.

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[east302]

It looks like it feeds the interior lights as well from splice 210...did you get into those as well? The ashtray lamp bulb and connector 298 may be a place to start.

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I see three location diagrams for C298, these are for a 98 model.

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[RawbDidIt]

Thanks for the diagrams, hadn't seen these in my search. I'll take a look tomorrow. When I unplug the headlight switch the current drops to an acceptable range, so that rules out the power mirrors (theoretically). I'll have to check the interior lights tomorrow after work. Correct me if I'm wrong, but if disconnecting the headlight switch kills the drain, and it isn't the exterior lights, the only components left to check would be the ashtray light, the power mirror switch and the power window switches/master power window cluster on the driver's side door, right?

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[east302]

I’d agree with that, it looks like the ashtray light, all of the window switch illumination bulbs and the Homelink (if you have it) are on that circuit.

The mirror motors themselves are on a different circuit so they should be out.

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[east302]

I’d almost wonder about your headlight switch, if the dimmer wheel switch is sticking.

 

[RawbDidIt]

Headlight switch is brand new.

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[RawbDidIt]

Update: not the ashtray light, not the door illumination for the power mirror, power windows, or power lock switches. On the plus side, the bulb was garbage, so I needed to replace it anyway. I'm trying to stay positive, but this is quite frustrating. I hate electrical problems. I appreciate the help this far, please keep it up.

I have an edit from a previous statement. I must have messed up the reading, when I unplug the headlight switch there's no change in the reading.

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[east302]

Hmm, it looks like the headlight switch is first in line except for a “headlight control module” on “luxury” models. I have no idea what that is (maybe automatic lights) or if you’d even have it, but here’s the location diagram. It looks to be under the driver dash somewhere.

So pulling the fuse stops the draw but pulling the headlight connector does nothing? So it’s got to be something between it and the fuse, right?

Do you have the second (Orange, circuit 240) wire coming out of that fuse position going to the convenience center and then to the headlamp module? It connects to the convenience center with C210, here’s the diagram (couldn’t find a pinout but it’s cavity A).

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My diagrams are for a 98, for what it’s worth.

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[RawbDidIt]

I don't think it's a "luxury model". The only thing luxury about it is the power driver seat and the power mirrors. I think the luxury model had fog lamps standard, mine has none. As for the orange wire, I'm not sure, I'll check. Every component I've looked at has had a brown wire, often accompanied by a blue wire. But you're right, if disconnecting the headlight switch changes nothing it has to be between the fuse and the switch, or on a different leg of the circuit. Definitely no drain between the battery and the fuse, pulling the fuse stopped the drain. Battery still running strong, no charging for 3 days. Only difference is the fuse being pulled.

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[RawbDidIt]

Ok, I know where C210 is, I'll try to unplug that and see if that changes anything. If so, the wiring between that and the headlight switch is bad, so a new run of wire should fix the problem, right?

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