What does it mean?
B1693 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Accessory Dimming Control Circuit Low .
Symptoms
- Instrument, switch and radio backlighting does not work when the lights are switched on
- The dimmer wheel has no effect on brightness
- Panel lights flicker or come on only partly
- Illumination fuse blows, sometimes taking other lighting with it
- The problem started right after an accessory was fitted or the dashboard was worked on
Likely causes
- Short to ground on the illumination circuit behind the dash, often at a bracket edge or where a wire is trapped by a screw
- Aftermarket accessory such as an audio unit, camera or extra lighting connected into the dimming circuit and drawing too much current
- Water damage behind the dashboard from a leaking windscreen seal or a blocked drain
- Illumination bulbs or LED panels shorted inside a switch pack or a heater control panel
- Damaged wiring in the steering column loom, where movement and tilt adjustment wear the insulation
- Corroded connector at the instrument cluster or the switch pack
- Shorted illumination driver inside the body control module
How to fix it
- Switch the lights on and check which illuminated areas are affected, since a shared symptom points at the common feed
- Check the fuse and look at the commanded dimming value on live data to see whether the module is trying to drive the output
- Disconnect any recently fitted accessory and see whether the fault clears, since incorrect connections here are very common
- Unplug switch packs and the instrument cluster one at a time to find the branch causing the low reading
- With the branch disconnected, measure the resistance between the dimming wire and ground to confirm a short
- Inspect the wiring behind the dash and along the steering column for trapped, chafed or water damaged sections
- Repair the wiring or renew the faulty switch pack, then verify that the brightness changes smoothly across the full range of the dimmer