Gauge lights peskiness mod
If you use your headlights in the daytime the gauge lights always step down one increment requiring it to be reset for full brightness every time. Need to turn 'em on for rain? Need to see the Speedometer with sunglasses on, sheesh! And you have to reach through the steering wheel to get to the control switch. Which is also integrated into the gauge assembly. One Insighter on the message board reports intermittant function from his " " dimming switch. Its unclear if the switch is repairable seperate from the whole assembly! ($$$ OUCH!)
The following mod will fix this design oversight and move this frequently used switch's function, making it inexpensive and easy to replace.
One other minor "bug" will need to be allowed to keep the mod simple. Else the connection will need to be made on the back of the gauge unit which requires dash face disassembly. The backlights for the Hazard, Climate Control, FCD buttons and Power Window Master switch will also be disabled with the mod "on". But hey this mod is for daytime, right?
Pg. 10-7 of the factory ETM 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, Red/Blk, is in the middle near the locking tab. Pin 16 is Yel/Red. Pin 18 is Grn/Red. Cut the Red/Blk wire that is pin 17 about 2" back from the connector for easy splicing.
Option connector E is an ignition on 12v source, a blank spade integrated in the driver's under dash fuse box. When looking at the under dash fuse box for this connector it is the far right of three near the top edge of the box, immediately above a large gray plug in relay (turn signal/hazard).
The nearest easy ground point will be to remove one of the 10 mm hex head bolts that are the lower dash support just to the left of the under dash fuse box and install an eye connector.
Use the following diagram to make the bypass system. The use of a relay allows the headlights on warning to still function. The headlight warning is internal to the gauge assembly. When you defeat the headlight signal to the gauge, with key off the gauge CPU will not see that the headlights are on and no warning will sound.
Capturing and viewing this .gif with graphics or photo editing software restores its readability.
To try and narrate the low res of this diagram the wire on the top left is from the Red/Blk wire that is cut for the splice. The new added switch is in the middle. Top right is the return to the other side of the cut. The NC side of the relay is used. The relay coil is energized by option connector E (ignition on 12v source).
I selected Radio Shack's #275-248, $4.29, SPDT Miniature relay. This also allows for full assembly of this new "sub harness" on the bench and then slip it through a switch blank for the final four connections. The relay chosen and when wired as shown will fail safe. If the relay fails the headlights on warning will operate and the modification will no longer function. The gauge dimming will revert back to its original pesky operation.
The switch selection will be more one of style, I used Radio Shack's #275-1565, $2.59, SPST on-off (not momentary contact). Just keep in mind it should fit one of the blanks on the left hand side of the dash below the FCD button.
The photo below shows the relay as connected, close to the switch with the wires continuing through to the underdash.
WARNINGS and HAZARDS:
Any bright yellow connector or wire jacketed with a similar colored loom is part of the SRS system. Modifying, damaging or disconnecting these wires could cause IMMEDIATE Air Bag deployment! Serious injury or DEATH can occur if your "hit" at the wrong angle. The recommended procedure before performing _any_ electrical work on an air bag equipped car is to disconnect both 12v battery terminals (to help assure one won't spring back and re-make contact) for 2 minutes. The "firing" capacitor(s) need this much time to discharge completely.
The mod wires should be sufficiently short or tied such that the brake and or clutch pedal action will not damage them.
The coin box's action can allow the wires to be snagged during normal opening and closing unless the wires are routed carefully in this area.
Last updated: 12/7/04