HELP!

Service vehicle soon indication on the dash. When the car is running, I cannot switch between HI/LOW/Parking lights when the car is running. With the car NOT RUNNING but in the ON key position, I can switch with no issues... Any ideas?



I do have HIDs that have been installed for 5 years now without any issues. They run all day which I'm fine with but I need this issue cleared.

 

Correction I can toggle between light settings when in the acc position but not when I switch position in the ignition.

Checked relays, switch, fuses, cleaned grounds. .. still having the issue. Basic code reader doesn't pick up an issue either.

 

Anyone?

 

Could be your multi-function switch.
Here is a thread that might give you more information. I know it is not exactly the same problem but a lot of problems happen when that switch does not work properly or there is a grounding issue.
Click here-->https://montecarloforum.com/forum/in...unction+switch

 

Thanks. I was thinking that also and trying to find similar threads. It's just weird it works fine with the ignition on ACC but not with the car on.

 

Any one else?

 

Changed the multi function switch and still having the same problems. Finally got it to a shop for a quick check and the BCM spit out a list of issues such as some circuits being high, some circuits low, now my DRLS and left and right brake lights have went out and come back as they please, also showing a Class 2 data link malfunction. Mechanic told me to try checking all grounds but sounds like the BCM is almost dead. Another issue now is the car hesitates to crank/start when you turn the car off and restart it a few minutes later (say like making a run into the store). Acts as if the battery is nearly dead but that's not the case, battery reads fine and is tendered every 2-3 weeks, tested with no issues.

What do you guys think?

 

Anyone?

 

This could be grounds. Check the main grounds to the body by the battery and under the air filter box.

It could also be the ignition switch housing. It's a "conduit" for the Class 2 Serial Data Link that shares info. between the chip that's embedded in the lock cylinder and the BCM. My money would be on that.

Please keep us posted, and good luck!

 

Thank you I did just clean a few grounds except the one under the air filter box and it is starting a whole lot better. Now with the ignition box housing what could I do to check that?