This is the exact problem I’ve been trying to solve. Where are the ground points for the DOOR setting for the switch? I’ve had similar problems to your daughter’s truck. Door Ajar Warning light comes on, truck won’t lock when a door is open, etc. but no cabin illumination when the dome light is on DOOR. The ON setting works fine.

I cleaned door switches with contact cleaner to be safe but it didn’t fix anything. I also switched entire light housing with one from the junkyard. Same issue persisted.

Sorry for being absent, hopefully your issues are solved by now! I ended up replacing the door light switch from the dealer and all seems to be well now.

That is the most used switch in our rigs so it's worth the money, but I wasn't going to buy a cheap replacement from Amazon or eBay

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I don't know if grounds are your problem there. I have had mine for 6 months and have grounds that aren't in the best shape and it ran smooth. Even with a jacked up spark plug install and valve covers that had long been leaking all over the grounds and into the spark plugs as well. If you think it's not running smooth and its grounds, you should have noticed there are bad grounds instead of just buying parts (I used to do that a lot). Usually the fix is something small and inexpensive.

There are 3 grounds that I found, 2 that were dirty and needed cleaned.

#1. The 8 gauge wire to the driver's side engine block from the battery negative. That cable is only probably 3 feet long, the only side you need to worry about is attached behind the alternator right above the oil pan. If your valve cover has leaked for any period of time, that will be gummed up and needs sprayed with engine degreaser and scrubbed with a small steel wire brush. I did the Big 3 upgrade and put on a new alternator worth 240 amps, charges 200+ at idle. Part of the big 3 upgrade is a 1/0 gauge wire from battery negative to alternator, negative to engine (it replaces that nasty little 8 gauge wire I just mentioned), and a 1/0 gauge positive to the alternator. Then your alternator has a big ass cable directly to the battery, as well as the engine block has a big fresh clean ground to the battery. If you were going to upgrade ANY wires for grounds it should be those. I got my setup from Tucson Alternator in Arizona, and I am looking forward to firing it up after all of these upgrade. It still charged at 14.4 with all of this, until it warmed up, then it dropped to 13.6 and would drop to 13.2 if I had the headlights on. Now I expect it will be 14.2 to 14.4 for the next 8+ years with the oil leaks gone and those cables replaced/added.

#2. If you look at the firewall behind the passenger side valve cover/spark plug area there is a ground bolted to the firewall there, and it attaches down right underneath the back of the passenger valve cover, mine was nasty due to the valve cover leaks and I could only see where it attaches because the whole intake and manifold was off and out of the way. I didn't re check it after it was all back together, you might be able to manage cleaning that one just by taking off the intake but you won't be able to do a great job without spraying it. I liked the Mac's Engine Degreaser (NAPA) because it foams up after it hits the target and expands in all directions giving a 360 clean to where ever it lands.


#3 is right at the battery to the fender, nothing wrong with that one since it's not near the engine.

The post you quoted is from 2006

13.6V is the correct charge voltage when the battery is warm... 14.2-14.4 with a warm/hot battery will overcharge it. 13.2V is still not discharging the battery, so if only at idle not really a concern overall. If you drop below 12.6 with any regularity, then you have a problem you likely should fix.

All that said, I have still upgraded all the grounds and charging wires you mentioned - just to 4 gauge. No need to go overboard here. (also a 105A OEM Denso alternator from a different vehicle - I have no interest in decreasing my reliability with non-OEM parts in this location)

-Charlie

Good eye, I wasn't paying attention. I also need more posts as a new member so I can start a thread. !

Hopefully it helps someone in the future.

I just upgraded the alternator to a non-OEM 240 Amp and just started it up yesterday since I swapped valve cover gaskets and cleaning grounds. It starts at 14.3 and after an hour it had increased to 14.5. I might double check my connector at the alternator since there was 2 of us working on it and I don't remember plugging it in myself.

The OEM alternator just isn't going to suffice for my development project of a semi grade hydrogen generator. I'm guessing there is a battery temp sensor that reaches back to the ECU to lower charge at higher temperatures? I'm in new Mexico and it's 20 in the morning and 20-30 again by sunset, that's when I was working on it. Even in those temps the old alternator would drop charge with the headlights.

The temperature sensor to approximate battery temperature is inside the alternator. The charge voltage is not controlled by the ECU at all - it is completely contained in the alternator. (battery sense wire, turn on wire, warning out wire and main power lug)

The factory Denso alternators are not very good at low-rpm output, but they are ridiculously reliable.

-Charlie

I hooked everything up and I have power but no crank on starter- is there a ground that I'm missing? thanks!