FFUUU- Battery being drained by Stop Light circuit

[theholycow]

My wife's 2000 Isuzu Rodeo's battery is being drained by the "Stop Light" circuit. I checked all the brake lights and the brake switch, none are the problem. I unplugged two connectors from the ABS module but couldn't get the third unplugged. I dread having to chase down the shift interlock and cruise control.

Somebody please tell me something that'll make it all better.

Edit: I just spent 45 minutes getting access to the brake shift interlock and unplugging it. Did not help.

[mtheis]

I had a similar problem when the black plastic piece fell off the brake pedal. The brake lights wouldn't turn off unless i held the pedal up with my foot. It sounds like your problem might be a little different, though.

[theholycow]

Yeah, the lights work properly, only coming on when triggered by the pedal.

She's about to start commuting 160 miles per day to law school. We can't afford it but we're just gonna squeeze our budget more. I think it's time for her to get something more efficient...it could cost $200/month and we'd come out even. We're not 100% sure but it looks like that's the way things are headed.

Now I just hate the idea of trading/selling this thing with that problem.

[IMBoring25]

How did you conclude it's in the Stop Light circuit?

How did you clear the switch as a potential culprit?

What does the circuit diagram look like?

[Rope-Pusher]

How did you conclude it's in the Stop Light circuit? With a clash of cymbals

How did you clear the switch as a potential culprit? DNA check from a swab of the cheek didn't match the blood sample collected at the crime scene

What does the circuit diagram look like? Wars n capisters n rasisters n summer tham ennervated circuses.

Why do you call yourself boring - your fun to pester!

[theholycow]

How did you conclude it's in the Stop Light circuit?: I used a multimeter measuring current. It read .72 amps. Then I pulled fuses, one at a time, until it dropped to .0something. When I pulled the "Stop Light" fuse is when it dropped.

How did you clear the switch as a potential culprit?: I unplugged the harness from the switch.

What does the circuit diagram look like?:
+12v -> Stop Light fuse -> brake pedal switch -> all of the following:
- Transmission & anti lock brake systems
- Cruise control & shift interlock systems
- High mounted stop light
- Right stop light
- Left stop light

Do not want to chase it to the transmission (what's it doing there anyway?), cruise, and that one ABS connector I couldn't get undone.

[Rope-Pusher]

^ Now your Mooness, I may be just a caveman enginneer, who can't distinguish your schematics from a cave drawing, but shuddn't the current come straight to the switch first, or are they doing sumpin in a Neanderthal way, like using the switch to ground the circuit? Dome lamp switches in the doors frames used to operate this way. I think you can use your spirit box to check if this is the KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKs or not.

[theholycow]

It does go straight to the switch, except for the fuse...or am I misunderstanding what you have to say about that?

Ohhhhhhhhhhhh I think I get what you're saying. It can't be in the systems beyond the switch; it must be between the fuse and the switch.

[Rope-Pusher]

It does go straight to the switch, except for the fuse...or am I misunderstanding what you have to say about that?

Ohhhhhhhhhhhh I think I get what you're saying. It can't be in the systems beyond the switch; it must be between the fuse and the switch.

Bingo (pay me! - even a dumb caveman engineer gots ta eat, right?)

Hey, who sed ewe cud google me?

Actually, my brother is the lawyer you found the image of. They get to wear suits. Engineers don't even wear ties now, unless they are interviewing. If you find an image of a caveman with a pocket protector containing a 6" steel rule, a pen and a 0.5mm mechanical pencil, that would be me. (Yeah, it may be 6" long, but I don't use it often enough as a rule)

[theholycow]

Engineers hired to testify about technical things in court wear suits, right?

Unfrozen Caveman Engineer to the rescue!

[Rope-Pusher]

Engineers hired to testify about technical things in court wear suits, right?

Unfrozen Caveman Engineer to the rescue!

Professional witni (plural of witness, right?) engineers? We sneer at them!

[IMBoring25]

Given all that, between the fuse and switch does sound like a good bet. 16.7 Ohms sounds like a fairly low-resistance short, possibly in a chafed wire bundle or poorly-insulated connector.

As for the transmission input...It's always possible it's something else, but it seems a fairly direct way to implement the brake/shifter interlock that allows the shifter to be moved from park only when the brake pedal is pressed. If, meeting all the usual prerequisites but with the fuse pulled, the transmission won't move out of Park, that's what's going on.

[theholycow]

Damn you electric educated folks...how are you getting 16.7 ohms out of anything I posted? There's something here for me to learn.

As for the shift interlock, that's handled by a solenoid at the shifter inside the vehicle. I had to take apart the entire console area to reach it.

[Rope-Pusher]

Damn you electric educated folks...how are you getting 16.7 ohms out of anything I posted? There's something here for me to learn.

They can see you through your internet connection.
Soylent Green is people!

[theholycow]

Soylent Green is people!

That movie was nowhere near good enough for the notoriety it has gained.