[lonestar2]

Old time member, new internet provider and new user name. Originally known as lonestar
Does anyone know what would cause the dash lights to vary intensity randomly? It acts like a loose connection, but I have no idea where to start looking. These are the backlights for illuminating the environment controls, instruments and various switches. Sometimes, they are at maximum intensity, other times, they flicker or vary in brightness, with no discernible cause.

 

[cart7881]

Welcome back.

For the light dimming circuit, most of the controls, except the instrument cluster share a single ground. Maybe check that. In the engine compartment, remove the air filter case. Behind it, mounted to the fender wall with a single bolt, is a small black plastic box. It will have some black wires going into it. Remove the attach bolt for the box and clean the box tab and the fender wall at the attach point. Let us know if there is an improvement.

If the instrument cluster lights are also affected, it may indicate a deeper problem. The instrument cluster ground is under the driver's seat. The cluster lights are controlled by the BCM over the Serial Data Bus.

 

[esmth]

what year truck? If you live in a place where they slap registration/inspection stickers on the lower right corner of the windshield, as you drive around the sticker cast a shadow over the light sensor on the dash and cause the lights/dimming to come in and out. I experienced this and it was really strange before I realized what was happening, lol.

 

[cart7881]

I don't think these trucks are that sophisticated as to have auto dimming on background lights. The truck has auto headlights and that sensor determines whether the DRLs or the headlights should be on. Probably what you were seeing was the background lights turning on and off when the blocked sensor was causing the headlights to switch on and off.

 

[esmth]

ah that makes a lot of sense. thanks. I also pulled the DRL (I think?) relay, so the lights only come on when the sensor sees it is dark out. By default on my truck they seem to stay on all the time otherwise.

 

[cart7881]

Yeah, in stock configuration there will always be a headlight on. It will either be in DRL mode or headlight mode. You can turn them off with the headlight switch, but only for the one drive cycle. Key off, key on, back to auto mode.

 

[rinabilly158]

I’m new


Sent from my iPhone using Tapatalk

 

[t-bone]

Welcome back