In an effort to spare some fellow owner the same pain I
went through, I have compiled a fairly logical theory of
operation and troubleshooting procedure for headlight
circuitry of a 1987 or later Volvo 240 series .... Please
critique and correct as you see fit, to make this
document better. I will post the completed version on my
web-page after I take pictures, and develop the
flowchart.

If you spot an error PLEASE OFFER CORRECTIONS

This is based on a 1987 245DL.


The basics of the system are that the Light Switch feeds
voltage to the Headlight Relay which supplies triggering
voltage to the Step Relay. The Step Relay supplies
current to the Hi/Low head lamps through the Lamp Failure
Relay (bulb failure warning sensor).



The Light Switch is located on the dash board to the left
of the steering wheel
------------------
Terminal #1 12V input from fuse #1
Terminal #2 12V input from fuse #1
Terminal #3 12V output to
Terminal #4 12V output to Headlight Relay


The Headlight Relay inside of the firewall near the
drivers left foot. Remove the toe panel and locate a
small 1"square silver Bosch relay.
-----------------------
Terminal #86 is fed 12V from the Light Switch
Terminal #30 is fed 12V from fuse #7
Terminal #87 is the 12V output to Terminal #56 of the
Step Relay

If the headlight relay was bad you would only have high
beams when pulling the high/low switch towards yourself.
In this momentary position, the current for the
headlights comes directly from fuse 2 and bypasses the
Light Switch and Headlight Relay. Test for voltage at
pin connector for terminal #86, If you have voltage
there, the Light Switch is good.

In an extreme emergency, (like this relay fails 20 miles
form home at 2am, etc.)you can jumper 30 to 87 and
hardwire the lights on.


The Step Relay is located in the engine compartment,
attached to the left fender near the battery. A large
silver relay.
-----------------
Terminal #30-red wire is fed 12 volts from fuse #???
Terminal #56-yellow wire is fed 12 volts through the
headlight relay terminal #87b when the head lamp switch
is on.
Terminal #56a-white/blue wire supplies 12 volts to the
high beams
Terminal #56b-yellow/white wire supplies 12 volts to the
low beam head lamps (through the bulb failure relay)

Test for voltage at the pin connection for terminal 56b,
which is one pin clockwise from the pin socket labeled S
in the relay base of the Lamp Failure Relay.
Terminal 56b is the output for low beams from the
high/low switch. If you have voltage there, the high/low
switch is good on low beams


The Lamp Failure Relay is located behind the facie of the
dash, just above the driver's left knee
-----------------------------------
Use a continuity meter on the terminals of the Lamp
Failure Relay.
54 connects to 54L and 54R, and S
57L connects to 58L,
57R connects to 58R.
56b connects to 56bL and 56bR.

Re-install the Lamp Failure Relay and test for voltage at
the input side the low beams.
If you don't have voltage there, the Lamp Failure Relay
is bad.


--
ovloV

http://home.attbi.com/~ovlov/