Dashboard light issue

[doncaruana]

An additional thought (hopefully you guys are still reading these cause I'm WAY over my head! )...When I checked the voltage at the fuse, I got no voltage at the fuse. On the E3 side, that is just the dark green wire from the dimmer to the fuse and the D4 side is the gray wire that goes to splice 217. But the difference in the "cavities" is just a fuse, meaning they should get the same reading, even though the test says to measure from D4 to ground. My point is, if I were to pull that fuse, shouldn't I get some voltage to ground on the E3/dark green wire side anyway?

As a corollary, I could just do a continuity check between that dark green wire and the fuse, right? And, similarly, I could do the same for the other side of the fuse and any of the gray wires that come out of splice 217 at the component where they connect, like, for example, the 4wd switch. And, following on that logic, let's say for the sake of discussion, that it is a single wire, that being the grey wire from fuse 14 to splice 217, if there is no way to get to splice 217 without pulling the entire dashboard, couldn't I make a "jumper" from that side of the fuse to one of those components gray wires? It looks like all the gray wires are just 22AWG wire, even from the fuse, so it doesn't seem like it would be routing too much through the wire.

Does any of this make sense? Again...WAY over my head...

 

[doncaruana]

I couldn't even get continuity from the dark green wire off the headlight switch to the fuse. Also noticed no fog lights come on. I think it's time for me to throw in the towel and take it to somebody...

 

[east302]

An additional thought (hopefully you guys are still reading these cause I'm WAY over my head! )...When I checked the voltage at the fuse, I got no voltage at the fuse. On the E3 side, that is just the dark green wire from the dimmer to the fuse and the D4 side is the gray wire that goes to splice 217. But the difference in the "cavities" is just a fuse, meaning they should get the same reading, even though the test says to measure from D4 to ground. My point is, if I were to pull that fuse, shouldn't I get some voltage to ground on the E3/dark green wire side anyway?

As a corollary, I could just do a continuity check between that dark green wire and the fuse, right? And, similarly, I could do the same for the other side of the fuse and any of the gray wires that come out of splice 217 at the component where they connect, like, for example, the 4wd switch. And, following on that logic, let's say for the sake of discussion, that it is a single wire, that being the grey wire from fuse 14 to splice 217, if there is no way to get to splice 217 without pulling the entire dashboard, couldn't I make a "jumper" from that side of the fuse to one of those components gray wires? It looks like all the gray wires are just 22AWG wire, even from the fuse, so it doesn't seem like it would be routing too much through the wire.

Does any of this make sense? Again...WAY over my head...

Yes to all of the above. With the fuse in place and headlight switch on, you should get something close to battery voltage when probing from the fuse test point to a ground.

If you have no continuity between the headlight switch connector (dark green wire) and the upstream side of the fuse when it is removed, then that should indicate a wire issue. On the plus side, that entire circuit should be reasonably accessible. Going by memory, but there should be two screws visible inside the fuse panel. Take those out and the fuse block pushes into the cab.

The bulk dash harness is clipped to the back of the dashboard, unfortunately. Nothing really moves back there, so a damaged wire seems a bit unlikely. Yes, you’d need to pull the dash to get to all of that.

 

[doncaruana]

Thanks for all that!

I tried doing a jumper wire directly from the headlight switch/dark green wire to the fuse terminal and got nothing. I even tried doing a jumper from the switch to the gray wire on the transfer case switch and still got nothing. I'm no stranger to electronics at all, but I certainly could have been doing something wrong. But it seems like there might be major issues there.

When I had it the fuse panel open, I tested fuse 15 (DRL Relay/Fog Lamp Relay) just to make sure I had a good ground and got 14 volts on it. Do we know how much voltage would normally come out of the dimmer circuit at max? Maybe, for a real hack, I could just try to jumper off that one to see if anything would illuminate at all. I'd hate to put too much through it through and burn everything out.

 

[east302]

If you jumped headlight switch power (orange) to the dark green on the same connector, do any lights come on?

 

[doncaruana]

If you jumped headlight switch power (orange) to the dark green on the same connector, do any lights come on?

I will try that later or tomorrow.

 

[doncaruana]

Well - a lot of other stuff happened and I didn't get around to trying that. And I'm glad I didn't.

The "other stuff" involved my dad, who has a 97 Suburban, so essentially the identical electrical and has no issues. I took my meter and tested the voltage to ground at fuse 14 and got 0.11 volts with the dimmer at max and about 0.07 with it at minimum. So I have no idea what that test where you're supposed to check for more or less than 10 volts is doing.

 

[doncaruana]

And another update... This one is a little embarrassing but the info is misleading (at least to me).

I had checked fuse #14 and it was fine. For the record, hers what that fuse is for:
14 - ILLUM 10 Amp (Red) - 4WD Indicator Lamp, Cluster, HVAC Controls, Chime Module, Radio
Illumination, Instrument Panel Switches, RR HVAC Controls

It would have to be that one, right? Turns out...THIS fuse was blown:
9 - Park Lamps 20 Amp (Yellow) - License Plate Light, Park Lamps, Tail Lamps, Ashtray Lamp, Door
Switch Illumination, Headlight ON Warning, Side Marker Fog Lamp Relay, Clearance Lights, Heater & A/C
Illumination

I haven't quite figured out how the dashboard smack would have helped before it blew. Is it possible the dashboard smack was related to another issue that eventually blew the fuse? A fuse seems like a pretty binary thing that physical vibration wouldn't affect much.

 

[Hoesgottaeat2]

Sometimes if a fuse element is just “cracked” and not fully “blown”, I can see how it would work by tapping it. Similar to a light bulb with a compromised filament.

Sounds like you found the issue? Thanks for following up with us with the resolve.

 

[doncaruana]

Sometimes if a fuse element is just “cracked” and not fully “blown”, I can see how it would work by tapping it. Similar to a light bulb with a compromised filament.

Sounds like you found the issue? Thanks for following up with us with the resolve.

Yeah, it appears to be fixed. I guess the circuit on #9 needs to be active or the illumination doesn't do anything. If that's in the stuff east302 posted in here I totally missed it! I'm hoping it sticks and, if so, thankful I don't have to tear out the dashboard!