Check engine light comes on when I turn on bed lights????

[Gladiator Brad 704]

Driving yesterday morning and went to turn on the lower fog lights in the bumper. Accidently turned on the courtesy lights in the bed. The check engine light came on. Turned the bed lights off the check engine light went off. This was while I was moving down the road. Reached my destination. Shifted to park same result with the engine running or off. Anyone have a theory on this.

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[TestMule]

Can we ask that you take a pic of this?

I know my cargo light indicator comes on in the dash when I turn them on. I've never seen a CEL come on when the cargo lights are on.

This is what the cargo light indicator looks like:

 

[Gladiator Brad 704]

This is it . Comes on and off in relation to the bed lights.

 

[Hootbro]

Those two things should not connect to each other unless you got wiring problem somewhere chaffing into possibly the CAN BUS and/or you have a common connection point with maybe corrosion across a connector.

If you can get a reader on the OBDII port and see what if any codes are on there when you have the light on may give insight to what tripping that and can narrow it down.

Bed lights are controlled through the BCM. MIL light posting comes off the PCM.

 

[Gladiator Brad 704]

If I am understanding you correctly , there is no comonality between the bed lights and the check engine light. The check engine light is a completly seperate computer and origin point.

 

[j.o.y.ride]

Would help to know which code is being thrown by the truck

 

[Hootbro]

If I am understanding you correctly , there is no comonality between the bed lights and the check engine light. The check engine light is a completly seperate computer and origin point.

Nothing I can see other than can bus. Some signal is crossing over at some common point whether it be a set of frayed wires possible touching or corrosion at a common connection point is my best ascertation. That is why getting to check engine light read to see what if any errors are posting. You may have can buss errors or possibly another circuit posting that can narrow down the search.

Your problem is weird enough that there is no magic bullet fix to say here is your exact problem.

 

[Gladiator Brad 704]

When I get a chance I will check for codes and repost.

 

[Hootbro]

Do the bed lights actually come on?

 

[TestMule]

Those two things should not connect to each other unless you got wiring problem somewhere chaffing into possibly the CAN BUS and/or you have a common connection point with maybe corrosion across a connector.

If you can get a reader on the OBDII port and see what if any codes are on there when you have the light on may give insight to what tripping that and can narrow it down.

Bed lights are controlled through the BCM. MIL light posting comes off the PCM.

Agreed on the potential for a shorted wire in the light circuit. I asked my question just to make sure it wasn't the light icon for the reasons you stated.

 

[Hootbro]

Agreed on the potential for a shorted wire in the light circuit. I asked my question just to make sure it wasn't the light icon for the reasons you stated.

Fact the rear bed light icon does not come on in the cluster gives me a pause for concern. If his bed lights actually go on and off and there is no stored OBDII fault codes, I would be leaning he has an actual instrument cluster issue.

If the bed lights do not come on/off with the switching, he may have a open ground issue that is back feeding looking for a ground.

 

[Gladiator Brad 704]

The bed lights do come on and off as they should. The insturment cluster was replaced under warranty about 6 months ago. It went totaly black. I seldom use the fog lights and probbly havent used them since the replacement of the cluster. I am sure in the past the engine light did not come on with the previous cluster. I do not get the light symbol posted by TestMule.

I will get the code read asap.

 

[sharpsicle]

I'm now also doubting there will be a code. Seems like something went wrong with the cluster replacement. I'd be interested to know if a DTC would cause the bed lights indicator to go on ?

 

[Hootbro]

Does the Engine light self test and come on and then go out after engine start?

 

[Gladiator Brad 704]

Yes

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