: service radar cruise control light / driving in tunnel

07-14-06, 09:16 PM
My sister has an 05 STS that has experienced the following problem several times. She has an appointment for the dealer to check it out, but the appointment isn't for another week.

The Problem:

While recently driving through the Harbor Tunnel in Baltimore (3 times in the past few weeks), her "service radar cruise control" light came on. She has traveled up and down the roads a bit since, but the light only seems to come on while she is in this specific tunnel (as she discovered today). She's also driven through the Ft. McHenry Tunnel without incident.

Anyone have any similar issue with the cruise?

07-17-06, 01:33 PM
Not a lot of ACC's out there and of those how many do regular "tunnel" driving (with variations galore there too) so it may be hard to find many comparable examples.

It does sound like it may be RFI related perhaps to one of the traffic sensors in the tunnel itself that has a sidereal or reflected frequency that is interfering with the unit.

Lots of things to sort out though like:

1) Is it in the same exact location/lane/direction of travel in the tunnel?

2) Does it come on and then clear or what does it take to clear the error?

3) Are there road/wall/ceiling mounted antennas or other devices that are in the area where the error occurs?

4) Is cruise set at the time or is it just on in FCA mode?

Not being familiar with the area I do not know if this is a toll-road but if not then perhaps taking someone along to document the trip and trying it several times might isolate it further.

Regardless the dealer will check to see what DTC codes the unit is throwing and try to isolate it from there.

If it is localized however then it sounds like a unique interference issue.

And always keep the transceiver window clean as that can/will cause error messages if it gets dirty...:bouncy:

Let us know what her dealer says and good luck!