My high beams have always been momentary contact only, that is, only stay on for as long as I keep the control arm on the steering column pulled towards me. This is with no lights on, or low beams on.

Reading this forum, seems like the headlights are supposed to cycle high/low through a latching relay (DAC 6902 Headlight Logic Relay Module).

I located and pulled said relay, cleaned the relay lugs and connector sockets with a tiny file and electrical contact spray.. No real dirt or corrosion to speak of.

Plugged back in, no change.

I then removed the cover of the relay and checked the board inside. Looked just about new.

Found a thread here about reflowing some solder joints, which I did. Tested the resistor and capacitor and both were in spec.

Plugged back in, still no difference.

Guess the next step is to to check power at the connecter socket coming on where/when its supposed to.

Then finally the control arm on the steering column if no success?

 

You don't mention which year car this is about.
Have you tried to push the stalk forward?
I seem to recall that is how the high beams work.

 

Didn't realize my signature (which lists my cars) doesn't show on the mobile version of this forum.

My car is a '95 XJS 2+2 Convertible 6.0L V12.

I tested the board by applying power and checking the mounted mini-relays with a continuity meter. Although both relays would click/close, neither latched.

I've tracked down a replacement DAC 6902 (SNG Barratt, $115.09),hoping that solves the problem.

The control stalk doesn't push forward, only pulls back. First thing I tried...

 

Common problem. Replacing that relay will solve your problem.

it did for me.

 

Replacing the 6902 relay did the trick. The high beams now latch and stay on as they are supposed to. Kudos to SNG Barratt, they had the best price on the part and shipped it fast.