Electrical short in the underwood light
05-29-2015, 03:37 PM
#1
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Electrical short in the underwood light
I was able to isolate a power draw coming from the underwood light. Does anyone know if this is on its own fuse? What fuse it is powered from?
The voltage reading is constantly above 14V and with everything turned off, my draw is less than 0.09V but when the light assembly has a bulb or is wiggled, it is pulling 1.4A. This is causing the battery to be low upon start, and I think it is causing my ABS & TC to fault.
Any help would be great.
The voltage reading is constantly above 14V and with everything turned off, my draw is less than 0.09V but when the light assembly has a bulb or is wiggled, it is pulling 1.4A. This is causing the battery to be low upon start, and I think it is causing my ABS & TC to fault.
Any help would be great.
05-30-2015, 12:52 AM
#3
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St. Jude Donor '08
Bar
The BCM has a SLEEP MODE. When the car is locked,, the BCM will enter a security / sleep mode. After (APPROX 12 min) it will enter SLEEP/SECURITY MODE. During sleep mode, the BCM will shed ALL module activity and should only draw 20-25 milliamps. It monitors and looks for NEW current draw events.
IF,,,,,,,,,,,,,,,, The BCM detects DC current activety, it will, come out of sleep mode.. Unless, the proper FOB.key chip credentials are met, it goes into SECURITY/ARLM MODE. If its not in security mode, it will turnon the BCM and allow it to control module functions.
After approx 12 min, if no other current draw activity is dected, it will go back into sleep / security mode.
HOWEVER,,,, If the BCM can not shed ALL the module actiity,, it will not be able to go to sleep and will depete the battery in short order!
If it isnt in alarm mode, the BCM will come out of sleep mode if it detects current draw and power the modules for approx 12 min and then, return to sleep mode.
If the current draw activity never goe away, the BCM will never return to sleep mode and the battery will be depleted.
YOU,,, have to sluth and figure out what is causing the BCM to NOT return to sleep mode.
BC
The BCM has a SLEEP MODE. When the car is locked,, the BCM will enter a security / sleep mode. After (APPROX 12 min) it will enter SLEEP/SECURITY MODE. During sleep mode, the BCM will shed ALL module activity and should only draw 20-25 milliamps. It monitors and looks for NEW current draw events.
IF,,,,,,,,,,,,,,,, The BCM detects DC current activety, it will, come out of sleep mode.. Unless, the proper FOB.key chip credentials are met, it goes into SECURITY/ARLM MODE. If its not in security mode, it will turnon the BCM and allow it to control module functions.
After approx 12 min, if no other current draw activity is dected, it will go back into sleep / security mode.
HOWEVER,,,, If the BCM can not shed ALL the module actiity,, it will not be able to go to sleep and will depete the battery in short order!
If it isnt in alarm mode, the BCM will come out of sleep mode if it detects current draw and power the modules for approx 12 min and then, return to sleep mode.
If the current draw activity never goe away, the BCM will never return to sleep mode and the battery will be depleted.
YOU,,, have to sluth and figure out what is causing the BCM to NOT return to sleep mode.
BC
05-31-2015, 08:48 AM
#6
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I have mine unplugged as well. Bills post makes sense, I left my drivers door open overnight and when I got in the car the next day I thought my battery would be dead but it wasn't so it must have went in the sleep mode after the programmed time and saved my battery. Door was still cracked and all interior lights were off so I thought dead battery.
Last edited by bjones7131; 05-31-2015 at 08:52 AM.
05-31-2015, 08:53 AM
#7
Le Mans Master
Left mine plugged so I don't get crap in the connectors and just took the bulb out...
05-31-2015, 09:53 AM
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I immediately thought of UNDERWOOD DEVILED HAM but underboob is good!!
You stated: "my draw is less than 0.09V but when the light assembly has a bulb or is wiggled, it is pulling 1.4A. This is causing the battery to be low upon start, and I think it is causing my ABS & TC to fault."
The under hood light has a mercury switch which turns it on. The light is controlled by the BCM and the BCM will turn it OFF after approx 12 min if the circuit is not disturbed.
If the light is turning on when the hood is shut, you could have a bad light switch..
When you wrote- 0.09V,, I suppose you really wanted to write 0.09 amps ( which is still too high)
BC
You stated: "my draw is less than 0.09V but when the light assembly has a bulb or is wiggled, it is pulling 1.4A. This is causing the battery to be low upon start, and I think it is causing my ABS & TC to fault."
The under hood light has a mercury switch which turns it on. The light is controlled by the BCM and the BCM will turn it OFF after approx 12 min if the circuit is not disturbed.
If the light is turning on when the hood is shut, you could have a bad light switch..
When you wrote- 0.09V,, I suppose you really wanted to write 0.09 amps ( which is still too high)
BC
Last edited by Bill Curlee; 05-31-2015 at 09:58 AM.
05-31-2015, 10:15 AM
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I immediately thought of UNDERWOOD DEVILED HAM but underboob is good!!
You stated: "my draw is less than 0.09V but when the light assembly has a bulb or is wiggled, it is pulling 1.4A. This is causing the battery to be low upon start, and I think it is causing my ABS & TC to fault."
The under hood light has a mercury switch which turns it on. The light is controlled by the BCM and the BCM will turn it OFF after approx 12 min if the circuit is not disturbed.
If the light is turning on when the hood is shut, you could have a bad light switch..
When you wrote- 0.09V,, I suppose you really wanted to write 0.09 amps ( which is still too high)
BC
You stated: "my draw is less than 0.09V but when the light assembly has a bulb or is wiggled, it is pulling 1.4A. This is causing the battery to be low upon start, and I think it is causing my ABS & TC to fault."
The under hood light has a mercury switch which turns it on. The light is controlled by the BCM and the BCM will turn it OFF after approx 12 min if the circuit is not disturbed.
If the light is turning on when the hood is shut, you could have a bad light switch..
When you wrote- 0.09V,, I suppose you really wanted to write 0.09 amps ( which is still too high)
BC
I was on my phone for the original post and those damn little buttons and auto correct are a pain in the a$$. Yes I did mean 0.09A with the light disconnected and 1.4A with it connected, and yes it should have read under hood.
I have been doing a little checking and I am getting a reading of 0.4 Ohms of resistance from the ground near the passenger headlight to the negative terminal. Seems to be a little high to me, but would like to know your opinion. I am inclined to begin pulling all of the ground connections and checking for corrosion and cleaning.
05-31-2015, 10:56 AM
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Its a little high for a short run of wire. Make sure the OHM Meter goes to ZERO when the leads are shorted.
Along with making sure that the gorund connections and connector pins are clean,, Make sure that the male and female pins have proper insertion compression. Do a pin pull test to insure that the two pins are making proper contact.
DO NOT use dielectric grease in the pins
BC
Along with making sure that the gorund connections and connector pins are clean,, Make sure that the male and female pins have proper insertion compression. Do a pin pull test to insure that the two pins are making proper contact.
DO NOT use dielectric grease in the pins
BC
06-19-2015, 03:56 PM
#11
Racer
My under hood /wood/ boob light won't come on, good bulb
It was fun looking for the problem under a boob but no luck. Then I ate some Underwood chicken, hoping for a tip in the bottom of the can but, no, still no help. So, help please.
2003 C5:
Maybe following some of these troubleshooting tips given above will solve my problem but, my under HOOD bulb looks A-OK, solid filament, etc but does not come on. So, I will check for current with a meter, see if I can find that mercury switch and other connector to see they're ok.
Great info here, thanks!
Update: no power at the bulb connectors, so I put a DC meter on that 2 prong connector by the headlight, no power there either. That should be 'hot' all the time right, and the mercury switch activates the hood lamp when it's opened, turns it off when shut? I'll try one more time with ignition to on, maybe it's a 'wake' issue as in the excellent guide above from Bill Curlee. Also trying to figure out how to get my dead brake fluid sensor out to replace it, pinch and pull? You can do it with fluid in there still I assume. A different thread, sorry.
2003 C5:
Maybe following some of these troubleshooting tips given above will solve my problem but, my under HOOD bulb looks A-OK, solid filament, etc but does not come on. So, I will check for current with a meter, see if I can find that mercury switch and other connector to see they're ok.
Great info here, thanks!
Update: no power at the bulb connectors, so I put a DC meter on that 2 prong connector by the headlight, no power there either. That should be 'hot' all the time right, and the mercury switch activates the hood lamp when it's opened, turns it off when shut? I'll try one more time with ignition to on, maybe it's a 'wake' issue as in the excellent guide above from Bill Curlee. Also trying to figure out how to get my dead brake fluid sensor out to replace it, pinch and pull? You can do it with fluid in there still I assume. A different thread, sorry.
Last edited by DWC4; 06-19-2015 at 04:37 PM. Reason: C5