2G Power Draw on Ignition Off

[H4G64T]

Cannot believe how hard this is to find, what should be the power draw for a correctly functiong, fully loaded, 2G DSM?

 

[turbodude]

Anything between 25-50 milliamps is considered normal current drain. If your seeing anything above 100 milliamps or 0.1 amps at Ignition off, then you got a leak somewhere that needs to be addressed.

 

[H4G64T]

Okay we are working on my friends 99 GSX. He is getting 200 to 400 milliamps. We know that the drain is on the engine bay fuse labeled room lamp. With all fuses out from under the dash, the drain doesn't drop at all. We are at a loss.

 

[turbodude]

Okay, so you narrowed it down to the room lamp fuse under the hood, which is a 10 Amp fuse. If that in case is the circuit that is causing the drain then pulling the fuse will stop the excessive current draw correct? Just wanted to make sure we are on the same page.

If your Current draw ceases, or goes back to the aforementioned acceptable levels after pulling that fuse then that is the circuit with the draw. From there it should be just tracing the circuit from front to back looking for possible shorts.

In this case, i would start with all the interior convenience lighting (The lights that turn on when you open a door). Such as under the dash, dome light's, rear hatch light, etc. Make sure to put the fuse back in, then check first for burnt out bulbs, or ones that appear to be dimmer than they should be, as that would be the easiest sign of a possible short. If that yields no results then start measuring current draw at each socket individually until you can find the culprit.

As a heads up, i've seen the dome light before as a major culprit of current draw in other cars. Sometimes condensation builds up under the headliner and zap, there's your problem, So i would check that first. Sometimes the actual switch itself that selects if the lights come on when you open the doors shorts out. when your measuring for current draw, make sure to actually toggle all the switches on and off where applicable and open and close the doors as you do the readings. Take note on your meter when doing such actions and you should be able to pinpoint it in a jif.... Good luck man

 

[H4G64T]

Yes the drain goes away with that fuse, but that fuse controls a ton of systems.

Couple of things that will help with this. We began by chasing down a large 2000+ milliamp power draw to the OEM amplifier. Both power wires going to the amp are grounding out somewhere. The owner of the car then recalled when rewiring the amp harness he snipped the power and ground wire together causing the circuit to complete. He said he saw a flash from under the dash and upon checking he found the amp fuse was blown. He thought that was the extent of it because all other electronics work with no issues that are observable. Now he obviously knows a wire somewhere for the amp is burned.

So what we are trying to figure out from that is besides the amp from fuse 1 under the dash, does that split off into anything else?

From there we know the wire from that fuse box makes it's way into the engine harness to go to the room lamp fuse. What would be the best way to determine the wire from the fuse box into the car is okay? What would be the best way to locate any other burnt wire pre-fuse box but post entering the car.

Can we just remove the bulbs from the lighting system and check the draw again to see if it drops? Would that be easier than probing all the connections themselves?

Also this fuse is responsible for battery back-up to the multiple ECUs and the ETACs, how would we effectively test those systems?

 

[turbodude]

Okay, try this if you have not already...

Make sure your battery is first disconnected and that there is no residual voltage left. If you let the car sit for 20-30 minutes after disconnecting the battery this is usually more that enough time to suffice.

Grab your DMM and set it to continuity. Connect your COM port to a solid chassis ground with an alligator clip and take your other probe and start touching the ends of the wires in question. (With continuity it really doesn't matter which one is grounded but for good practice i always ground the COM probe). Start with the one you mentioned that runs from the fuse box under the hood to under the dash. Make sure when doing this you pull the fuse to isolate that specific wire your testing. If there is any kind of short in that wire then you should here your DMM beep since a short would complete the circuit and boom, you found your culprit. If not, move on to the next. Your bound to find the connector, wire, stuck relay, etc that is causing this issue.

I honestly don't know what else fuse-1 under the dash splits into, if any. I hope you can nail this as i know how frustrating things like this can be. laterz

 

[H4G64T]

Apparently it splits to the radio and the amp and that is it.

 

[H4G64T]

Ok here is what we have determined.

- Car has four points of parasitic draw. With all 4 systems disconnected we are at 27 mA of draw, which is where we need to be.

- 1 of the draws is in the circuitry for the power windows and power seat, that's a whole other mess that we have been working before all this.

- The other three draws are all related. The amplifier, the radio and the CD changer. We know the circuitry is from fuse 1, and that splits off to the radio harness and the amp harness, and from the amp harness it splits into two, both go to the amp connector. They are constant power sources, which means they are controlled by the grounds. Since the grounds aren't controlling them, through testing we know that the power wire has to be grounding out pre-split to the radio.

The tricky part is trying to figure out how that coincides with the CD changer, which does not get powered off fuse 1. My hypothesis is that the wire that powers fuse 1 also splits off and runs directly back towards the CD changer. So I am assuming that the problem is going to be between the connector coming into the car and the junction that wire splits at. Problem is, I can't seem to figure out if this is true or not.

Okay, I see that the wire coming off the fuse box is R/B and I see the power wire from the CD changer is R/B and it says it goes back to J/B with a B in an upside down triangle. So they all run off the same circuitry.