Jump to content

Headlight leveling motor AMR2706


tychoS
 Share

Recommended Posts

I have a little problem with the headlight adjustment on a DiscoveryII

It is fitted with electric headlight adjustment, the type where there is a 4-position knob on the dash to set the desired headlight level.

The bottom headlamp adjuster is a little electric motor, apparently part number AMR2706

As the vehicle came to me, the headlamps were adjusted sort of ok-ish, but the wires to the electric motors were un-plugged.

I plugged them in, both the motors made a little "motor running sound" and both their adjusters were drawn into the fully-in/headlights-fully-down position. Then "the lines of communication" with these motors broke down.

Turning the knob on the dash has no effect. No fuses are blown.

But the headlights are pointed down to the ground to a degree that makes it undriveable at night.

There is a 13 mm plastic "nut" on top of the AMR2706. Turning it makes a ratchetting sound, but does not affect the level. I took it for a manually override, but perhaps it is something else?

The AMR2706 has a 3-terminal plug. What is the pinout and protocol?

I would love trying to diagnose the problem by testing the motors on the bench with an external power source. Is it eg. ground, 12V and a pulse pin like for a stepper motor, or ground and a pin to make it move one way and another pin to move the other way with the duration of time controlling how far?

Link to comment
Share on other sites

Looks like it's a pretty simple system.

The red wire going to the headlamp motor is a +ve feed from fuse 11. The red wire going into the switch comes from fuse 33.

I'd start by checking fuse 33, and after that the wire from the switch's pin 2 to the headlamp motor pin 2.

post-18506-0-30567700-1423830373_thumb.png

Link to comment
Share on other sites

Don't give direct feed to the motors cos you might burn them as they have an internal potentiometer and the

expected feed is below 12V all the pointed fuses above are good IMO the problem is within the switch:

you should remove the switch put ohmeter where the blue/pink and red/orange wires were connected(pins 2-4) and see if you get those resistances by turning the switch through all the positions but if you get open circuit once or the ame as for 0 position on all then that's the problem if you see what i mean

The difference in the voltage output from the headlamp levelling switch and the

battery voltage is compared by a potentiometer in the LH/RH headlamp
levelling motors. When the headlamp levelling switch is moved, the differing
voltage causes the motor to operate until the potentiometer output equals the
switch output. The motors stop and set the headlamps to a position which
corresponds to the headlamp levelling switch position.
The input voltage to the headlamp levelling switch passes through the following
resistors depending on switch position as follows:
Position 0 = 120 Ohm (R5) and 390 Ohm (R6)
Position 1 = 120 Ohm (R5), 20 Ohm (R4) and 390 Ohm (R6)
Position 2 = 120 Ohm (R5), 20 Ohm (R4), 100 Ohm (R3) and 390 Ohm (R6)
Position 3 = 120 Ohm (R5), 20 Ohm (R4), 100 Ohm (R3), 75 Ohm (R2) and
390 Ohm (R6).
  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy