The Service Engine Soon light in my wife's '98 Grand Caravan is on, so I cycled (on/off on/off on) the key and the light flashed 1 2 6 6 6 6 5 5, so I think the DTC is 6666, but I've been unable to find what that signifies. BTW, the odometer does not indicate a "P0" code - when the key is on, the mileage (73K) is all that shows.

Haaaaaaalp!

TIA

j

 

Using the key dance you're reading MIL codes and they are all two digit codes. Your model year won't display powertrain codes (PXXXX) on the odometer. You have to connect a scanner to read those codes. Free at AutoZone or the like.

You're getting two 66 codes for some reason which is a CCD data bus code meaning either the BCM or TCM isn't sending data. Any other symptoms? Two 66 codes may mean neither the BCM nor TCM are sending data (a guess).

 

Nuts! Tnx for the info. There were no symptoms, the Service Engine Soon light just came on a couple of days ago. Other than that, the van drives fine. I guess I need to put some electrical tape over the SES light. :-) I'll do some research on BCM and TCM (transmission control module?).

j

 

Oh, another thing: I connected a scanner to the diagnostic connector but it came up clear, no codes at all.

 

Did it not power up? That could be related to the 66 code but I would think you would see symptoms like erratic instruments, rough/no shifting, no starts etc. Try disconnecting the battery for 5 minutes. That should clear the codes and turn off the light.

BCM - Body control module. It's the heart of the CCD data bus system and controls most of the accessories in the van. It's mounted on the junction block

TCM - Yup, transmission control module. It's mounted just forward of the power steering reservoir.

 

Tnx Cougar41, disconnecting the battery reset the codes. I'm curious about what caused the light, but SWMBO is happy, so I'll live with not knowing the cause :-)

 

Far and away the most common cause of a data bus codes on third generation vans are cracked solder joints on the instrument cluster circuit board specifically, where the connector is secured to the board. The good news is the fix is free. Just retouch them with a soldering iron.

SWMBO - Had to look that one up but it sure is spot on. Ignoring it makes for a dark day.