Yes, it is a pesky design oversight!!!
The good news:
It looks like their is a relatively easy modification to allow an "override" switch to be installed. This would open the 12v signal to the gauge assembly when headlights or taillights are on, preventing the dim step down. The backlights for Hazard, Climate Control, FCD switch and the Power Window Master switch will also be disabled, but hey it daytime, right?
The concept is to simply turn off the 12v that is sent to the gauge when the headlights are turned on. Thankfully there is a connector that is (relatively) easy to get to.
Without advanced electrical knowledge and the Factory ETM its going to be a bit difficult. Pg. 10-7 shows C404 in just the right spot both electrically and physically. Under the left side of the dash, in the immediate vicinity of the brake light switch. Light blue, 24 pin, 2 row. Pin 17 is in the middle near the locking tab. Pin 16 is Yel/Red. Pin 18 is Grn/Red. Pinout #17 Red/Blk and add a switch to open this branch.
With headlights on and this new switch off (open) the gauge should "believe" that headlights are off and maintain full daytime brightness.
The BAD news:
Your symptoms indicate a worn gauge switch. The factory service manual does not indicate that this switch is serviceable (although it might be). Also, removing the gauge assembly requires removing the dash face first. Increasing the difficulty of the task.
My best recommendation would be to install the modification. After all that's the feature we want. Then the need for a reliable switch in the gauge assembly will be moot. And you can wait 'til you have no choice in needing it to work. Then if something breaks along the way while trying to fix it you probably would have had to replace it anyway. :/
FYI: If you choose the gauge removal option be advised the Factory service manual states that the battery gauge may take up to 30 min of _driving_ to begin functioning again when its power is removed.
HTH!
And thanks for saving my gauge switch all the additional wear and tear.
The good news:
It looks like their is a relatively easy modification to allow an "override" switch to be installed. This would open the 12v signal to the gauge assembly when headlights or taillights are on, preventing the dim step down. The backlights for Hazard, Climate Control, FCD switch and the Power Window Master switch will also be disabled, but hey it daytime, right?
The concept is to simply turn off the 12v that is sent to the gauge when the headlights are turned on. Thankfully there is a connector that is (relatively) easy to get to.
Without advanced electrical knowledge and the Factory ETM its going to be a bit difficult. Pg. 10-7 shows C404 in just the right spot both electrically and physically. Under the left side of the dash, in the immediate vicinity of the brake light switch. Light blue, 24 pin, 2 row. Pin 17 is in the middle near the locking tab. Pin 16 is Yel/Red. Pin 18 is Grn/Red. Pinout #17 Red/Blk and add a switch to open this branch.
With headlights on and this new switch off (open) the gauge should "believe" that headlights are off and maintain full daytime brightness.
The BAD news:
Your symptoms indicate a worn gauge switch. The factory service manual does not indicate that this switch is serviceable (although it might be). Also, removing the gauge assembly requires removing the dash face first. Increasing the difficulty of the task.
My best recommendation would be to install the modification. After all that's the feature we want. Then the need for a reliable switch in the gauge assembly will be moot. And you can wait 'til you have no choice in needing it to work. Then if something breaks along the way while trying to fix it you probably would have had to replace it anyway. :/
FYI: If you choose the gauge removal option be advised the Factory service manual states that the battery gauge may take up to 30 min of _driving_ to begin functioning again when its power is removed.
HTH!
And thanks for saving my gauge switch all the additional wear and tear.
