On my 1994 XJ6 I have tried replacing the DBC10009 relay before in an effort to fix a problem where my front parking lights and rear taillights do not reliably come on with the switch on the dash.
Now I am experiencing the same exact problem with the car and if I reach over and flick the DBC10009 relay with my fingers, the lights come on but they will not stay on.
I.E. if I flick the relay so they come on, then shut the switch off and back on again, the lights will often not actually come on again unless I again reach over and flick the case of the relay.

 

Bad solder joint in the module, take it out of the case and reflow solder joints, that should help/fix it

Larry

 

I am looking at the inside of one of my malfunctioning DBC10009 relays and I see four separate relays inside that control four separate electrical circuits.
Can anyone tell me which relay inside the case is for the running lights (front marker lamps and rear taillights) ?

They are labeled like this on the outside of the case:

1 Auxiliary Positive
2 Sidelight Positive
3 Auxiliary Sidelight
4 Cigar Lighter

but there is no way inside the case to identify which is which exactly.

Here is a photo showing the interior of the relay.


Interior of DBC10009 relay

 

Just reflow them all

Larry

 

Last night I did finally try reflowing the solder points in a couple of the DBC10009 relays I have here that were exhibiting the symptoms. I was unsuccessful with the first relay but after doing about 40 - 50 percent of the points in the second relay I now have what I believe are reliably working taillights and front parking lights.

 

Steve,

Were you not able to access the other 60%-50% of the joints? As Larry said, it's a good idea to just re-flow and supplement all the joints you can access.

Cheers,

Don