The last electrical gremlin: automatic shifter backlight
Thread Starter
Heel & Toe
Joined: Dec 2003
Posts: 18
Likes: 0
From: Chesapeake VA
The last electrical gremlin: automatic shifter backlight
Many thanks to several members as I was able to use several threads to correct my electrical anamolies (most of which were occurring due to bad grounds) except for one in my 2003 convertible. When I exit the car, within 18 secs the mirror & dash lights go out, folllowed by footwell lights at almost one minute, and then both left & right hand door power control lighting about 20 secs later, but the backlight (light bulb) for the P R N D automatic shifter stays on for approx 15 minutes. I can't finds any specs on this but that seems like an excessively long time. I tried this a couple of times, and all of the times were close to what is listed above for each of the components. Rather than remove that lightbulb, I would like to hear from forum if you have seen this before and possible causes for such a long delay.
Melting Slicks
Joined: Jan 2009
Posts: 3,275
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From: Miami FL
I just went to check mine and it has the same sequence as yours, except that the PRND light goes out in sync with the first group.
This is the first time I hear about this and I really don't think that what I'm going to suggest you will fix it, but it will bring less heat to the area and draw less current from the battery.
Take a look at this post and scroll up and down to see pictures of the problem you will be preventing.
This is the first time I hear about this and I really don't think that what I'm going to suggest you will fix it, but it will bring less heat to the area and draw less current from the battery.
Take a look at this post and scroll up and down to see pictures of the problem you will be preventing.
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I know my PRNDL light does not stay on for 15 minutes. It goes out when the first group of lighting goes out.
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
The BCM has a dedicated single wire circuit just for the light. I know that seems weird but it is true. The BCM grounds that circuit to light the bulb and removes the ground to shut the light off.
The BCM is not turning it off as it should but when the BCM finally "goes to sleep" it ends up depowering that circuit. That is my determination.
I don't think the draw would be enough to drain the battery in a short time even if the BCM does not go to sleep. Putting in an LED would lengthen that time and solve the heat damage. The only fix I see for an OEM repair is to replace the BCM. There are plenty of cheap reman units for the late models like yours. Good used can be had from Marc at VetteNuts.net
Doing the relearn "handshake" between the PCM and BCM is a simple DIY and we can provide that for you if you go that route.
Mr. Sam
The BCM is not turning it off as it should but when the BCM finally "goes to sleep" it ends up depowering that circuit. That is my determination.
I don't think the draw would be enough to drain the battery in a short time even if the BCM does not go to sleep. Putting in an LED would lengthen that time and solve the heat damage. The only fix I see for an OEM repair is to replace the BCM. There are plenty of cheap reman units for the late models like yours. Good used can be had from Marc at VetteNuts.net
Doing the relearn "handshake" between the PCM and BCM is a simple DIY and we can provide that for you if you go that route.
Mr. Sam
Safety Car
Joined: Dec 2010
Posts: 3,938
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From: Fords, NJ
Take a look at this post and scroll up and down to see pictures of the problem you will be preventing.
Thanks
Thread Starter
Heel & Toe
Joined: Dec 2003
Posts: 18
Likes: 0
From: Chesapeake VA
The last electrical gremlin
Very informative. I ordered the LED bulb today and I think for now, will live with the longer delay until other BCM issues drive replacing it.....
I just went to check mine and it has the same sequence as yours, except that the PRND light goes out in sync with the first group.
This is the first time I hear about this and I really don't think that what I'm going to suggest you will fix it, but it will bring less heat to the area and draw less current from the battery.
Take a look at this post and scroll up and down to see pictures of the problem you will be preventing.
This is the first time I hear about this and I really don't think that what I'm going to suggest you will fix it, but it will bring less heat to the area and draw less current from the battery.
Take a look at this post and scroll up and down to see pictures of the problem you will be preventing.
Thread Starter
Heel & Toe
Joined: Dec 2003
Posts: 18
Likes: 0
From: Chesapeake VA
Last Electrical gremlin
I agree with you and I think, especially once I change to LED bulb (which I ordered today), that I can live with longer delay until other BCM issues occur.
The BCM has a dedicated single wire circuit just for the light. I know that seems weird but it is true. The BCM grounds that circuit to light the bulb and removes the ground to shut the light off.
The BCM is not turning it off as it should but when the BCM finally "goes to sleep" it ends up depowering that circuit. That is my determination.
I don't think the draw would be enough to drain the battery in a short time even if the BCM does not go to sleep. Putting in an LED would lengthen that time and solve the heat damage. The only fix I see for an OEM repair is to replace the BCM. There are plenty of cheap reman units for the late models like yours. Good used can be had from Marc at VetteNuts.net
Doing the relearn "handshake" between the PCM and BCM is a simple DIY and we can provide that for you if you go that route.
Mr. Sam
The BCM is not turning it off as it should but when the BCM finally "goes to sleep" it ends up depowering that circuit. That is my determination.
I don't think the draw would be enough to drain the battery in a short time even if the BCM does not go to sleep. Putting in an LED would lengthen that time and solve the heat damage. The only fix I see for an OEM repair is to replace the BCM. There are plenty of cheap reman units for the late models like yours. Good used can be had from Marc at VetteNuts.net
Doing the relearn "handshake" between the PCM and BCM is a simple DIY and we can provide that for you if you go that route.
Mr. Sam
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
Yep, I think you will be fine.
Also try disconnecting the negative battery cable for a few minutes. While disconnected I would even jumper the negative cable to the positive cable to help discharge any capacitors in the BCM. THIS IS NOT SHORTING THE BATTERY, it is out of the circuit.
This will just reboot the BCM. It's free and has fixed some PCM and BCM issues for some weird issues.
Mr. Sam
Also try disconnecting the negative battery cable for a few minutes. While disconnected I would even jumper the negative cable to the positive cable to help discharge any capacitors in the BCM. THIS IS NOT SHORTING THE BATTERY, it is out of the circuit.
This will just reboot the BCM. It's free and has fixed some PCM and BCM issues for some weird issues.
Mr. Sam
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