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Hummer H2For those who like a little more gleam to their Hummer, the H2 offers a similar rugged look as the H1, but as a lower cost, and with more added features, making it almost a massive luxury SUV.
Going through the circuitry here are some suggestions.
There are actually 6 indicators inside the Transfer Case Control Select Dash Switch, 5 LEDs and 1 filament bulb (night time illumination) interestingly the Neutral LED is handled differently from the others which may be why it works.
Neutral
4 Lo
4 Hi Locked
4 Hi
Rear Diff locked
These 5 LEDs (not the Neutral) are intensity controlled together by the interior lighting system i.e. they can be "dimmed" along with many other indicators, however they form a common wiring group which includes the Traction Control Switch, Ride Height Switch (if you have air suspension) and DRL (Headlamp Switch) Indicator, so if any of these work, the dimming wiring supply is OK. TIP check your dimming control switch setting.
The signals for each LED originate from the Transfer Case Shift Control Module which controls the LED corresponding the 4WD mode selected.
The switch has two connectors , C1 (8 Pin) and C2 (4 Pin), either connector being unplugged or having a wire loose could cause an issue with the LEDS (or switches)
To establish if its an "Indicator/LED" problem or hard mechanical fault, does the switch do anything i.e. can you hear anything engage/disengage or do any of the ranges change?
BTW driving (slowly) through all the 4WD combinations as this is a common fix for "SERVICE 4WD" issue.
If the transfer case actually changes 4WD modes but no lights it could just be a bad switch (pretty cheap on eBay) or a bad connector or wiring.
The "switching" is done by changing the resistance in a 2-wire circuit, any break in that circuit will render all switches inoperative, specifically C2 Pin A (Grey) or C2 Pin H (Light Blue)
This same problem just happened to me. I noticed that when I move the gearshift lever, it causes the orange “ 4 Hi” light to switch to a red “Neutral“ light. The red light stays ON while driving. If the gearshift is wiggled, sometimes the orange 4Hi comes back on. The t-case does NOT sound like it is changing gears when that happens.
I wonder if it could be a broken wire or bad connection at the gearshift?
Can anyone please point me to how exactly to pry out the cupholder area without damage, to gain access to the gearshift connector? I am sure I saw it on the forum somewhere but can not find it now.
