Under hood light
07-09-2016, 04:13 PM
#1
Instructor
Thread Starter
Under hood light
On my '01 convertible the under hood light has stopped working. Also the battery was dead this a.m. There is no power to the light and also no draw on the battery at this time. Is there a relay/timer on this light that could possibly be causing this problem? I was unable to locate one in either fuse panel. Until yesterday the light has been working as it should and I have had not battery problems prior to this. There are no codes on the DIC. Any help/suggestions would be greatly appreciated. thanks in advance.
07-09-2016, 04:43 PM
#2
Burning Brakes
That light should come off after a min or so after you open the hood and the doors are closed. I have notice sometimes that it stays on if the doors are open several time, I guess the timer on the relay get override. That has happened to me on car shows if I open doors too many time so I unplug the light switch as a precaution. I don't know if the relay is inside the light casing or if it's control by the same relay that control the interior lights when you close the car.
That's all I can think for now Omaha, hope you get the car going again and can solve the problem. Hopefully someone else will pitch in with other ideas... Good luck.
That's all I can think for now Omaha, hope you get the car going again and can solve the problem. Hopefully someone else will pitch in with other ideas... Good luck.
07-09-2016, 05:07 PM
#3
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The underhood light on my '03 goes off when I shut the hood - no time delay at all. If the hood is open, the light should go off in 10-15 minutes after opening the hood.
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SpeedRacerMach (11-07-2018)
07-09-2016, 05:45 PM
#4
Instructor
Thread Starter
Until yesterday mine worked the same way. My thought is that what ever controls the light shutting off after the hood has remained open for 15 or 20 minutes may have malfunctioned and caused my battery to go dead and also my be the reason the light no longer works at all. I just do not know what controls this. As I stated, there is no power at the light and I see no fuses that could be the cause. Maybe someone can let me know how this works.
07-09-2016, 06:29 PM
#5
Instructor
Thread Starter
No, the vanity lights do not work now and neither do the I/P compartment lights. Here's something else,...a couple days ago I replaced the driver's side sun visor and the new one has LED vanity lights, which by the way are a joke. I'm wondering now if my problems are caused by the new visor?? I'm thinking of just disconnecting the light on the new visor. I don't use it and it's worthless at best. So I must have a fuse somewhere that is blown or a "timer" that has failed. I appreciate the heads up on the vanity lights. Never made that connection, but then again, I'm old! Any ideas where or what this "timer" is?
07-09-2016, 06:33 PM
#6
Instructor
Thread Starter
The operation of the under hood light and several other convenience lights (glove box light, vanity mirror lights, and inside rear view mirror light) is controlled by the Body Control Module in conjunction with fuse #2 and relay #37 in the IP fuse box. Here is a wiring diagram:
Attachment 47998938
The left side of the diagram shows how this works.
When any of the lights in that circuit should be illuminated, the BCM provides the ground for the coil side of relay #37 to provide power through fuse #2 and then monitors the current flowing in that circuit and if the current flows for more than a specific period of time (about 15 minutes) the BCM drops the ground path to the coil side of relay 37 causing the circuit to become open and hence the lights go out.
If you have no voltage at the under hood light then your vanity mirror light and glove box light probably also do not function.
I would check fuse #2 to see if it is bad and also relay 37 to see if it failed in the closed position. If it failed in the closed position then any lights that were illuminated would have remained on until the battery expired...........
Attachment 47998938
The left side of the diagram shows how this works.
When any of the lights in that circuit should be illuminated, the BCM provides the ground for the coil side of relay #37 to provide power through fuse #2 and then monitors the current flowing in that circuit and if the current flows for more than a specific period of time (about 15 minutes) the BCM drops the ground path to the coil side of relay 37 causing the circuit to become open and hence the lights go out.
If you have no voltage at the under hood light then your vanity mirror light and glove box light probably also do not function.
I would check fuse #2 to see if it is bad and also relay 37 to see if it failed in the closed position. If it failed in the closed position then any lights that were illuminated would have remained on until the battery expired...........
07-12-2016, 03:49 AM
#7
Instructor
Thread Starter
Ok, I will update my progress on this little problem. I changed out relay #37 and all "appears" to be normal?? After driving the car some 25 miles or so, I noticed the battery voltage will not maintain over 13.6 volts. I think this is on the low side. Should be closer to the 14 volt range. I think my battery is getting close to replacement time. I disconnected the under hood light and when I disconnected the battery I noticed there is a click sound in the area of the right headlight. Can anyone tell me what that might be? If I reconnect the battery and then disconnect it again I can hear the click. Not sure if this is some sort of a "timer controlled" module/relay or what. Since I replaced relay #37 my discharged battery problem seems to have been solved. Ideas?? Thanks again.
07-12-2016, 01:56 PM
#8
Instructor
Thread Starter
The click you hear when disconnecting/reconnecting the battery is the headlight control module which is located below the right side headlight. Normal noise as that relay is powered at all times and not just when the ignition switch is in the ON position.
If relay 37 was stuck" in the closed position then any light in the "monitored load" circuit that was ON would remain ON and the BCM would not be able to turn it off based on the timer function by dropping the ground for the coil portion of relay 37. That would draw down the battery.
The replacement relay is allowing the circuit to function as designed and power off lights in the monitored load circuit after a short time.
If relay 37 was stuck" in the closed position then any light in the "monitored load" circuit that was ON would remain ON and the BCM would not be able to turn it off based on the timer function by dropping the ground for the coil portion of relay 37. That would draw down the battery.
The replacement relay is allowing the circuit to function as designed and power off lights in the monitored load circuit after a short time.
07-12-2016, 03:02 PM
#9
Le Mans Master
your DIC voltage will sometimes show a lesser voltage than the actually battery voltage... measure your battery voltage at the battery if you think it's low... and get it LOAD tested at a local auto parts store...
IF you ever have alternator trouble, be SURE you read the STICKY in the TECH SECTION about alternator design by dadaroo....one of his final contributions to the forum
IF you ever have alternator trouble, be SURE you read the STICKY in the TECH SECTION about alternator design by dadaroo....one of his final contributions to the forum
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SpeedRacerMach (11-07-2018)