A
AshMan40
- Jan 1, 1970
- 0
Hi all. This is my first post to this NG forum, so please be kind.
I am trying to repair a 12v latching relay for my Volkswagen Beetle
(~1975). It controls the dimming of the headlights (hi/lo).
The trigger is a momentary ground signal (S) which actuates the coil.
The arm that the coil pulls on has a plunger which toggles a rather
complicated see-saw arm which moves a contact between posts 56a &
56b. Also attached to the arm is a contact which connects to both
outputs (56a & 56b) while the arm is being pulled (I can actually only
see where it connects to terminal 56b on the actual relay). The
diagram may be a bit off since only one of the outputs is "hot" during
actual operation.
The below diagram came from the relay casing. Here is a pic w/ the
circuit diagram screened on the outside of the casing:
http://www2.cip1.com/PhotoGallery.asp?ProductCode=VWC-111-941-583
I've added all the terminal labels in parentheis.
The BAT terminal has constant 12v(+). The IGN terminal has 12v(+)
when both the ignition and the headlight switch are ON. The GRD is
connected to the momentary switch on the turn signal (I've confirmed
it grounds when pressed). The 56a & 56b circuits power the HI/LO beam
circuits, respectively. These are fused after this relay which means
this relay must flow all the current for the headlights.
I believe the mark on the contact that swings between the two outputs
indicates it is a latching contact which stays closed to one of the
outputs until the next activation of the coil.
The extra "swinging" contact to the very right of the diagram would
seem to apply power to both outputs for the brief time that the coil
is energized. The result is that you can dim the headlights w/o the
IGN being on and the headlights will momentarily light up.
The HI circuit is fused w/ two 16A fuses in parallel (total 32A), one
for each headlight. The LO is fused w/ two 8A fuses in parallel
(total 16A).
+-----------------------+
IGN | |
+(56)------|-------------+ |
| | |
BAT | | |
+(30)>-----+-------+ | |
| | + +
| | \ \
R? COIL=====\====<====\
| | \ \
MOM | | / \
GND(S)>----+-------+ + \+ + \
| | |
+-----+---+
| |
(56a) (56b)
HI LO
My problem appears to be the resistor located in parallel w/ the
coil. It is obviously burnt out on my relay. It looks like it
"popped". It is mostly black and I cannot make out the colored
stripes to determine the rating.
I'm assuming the resistor was protecting the coil. If it were to burn
out, wouldn't the coil then take the full current/voltage? I haven't
taken the relay apart enough to test the coil separately, but wired
normally it wasn't activating (which is why I opened up the relay).
While I could buy a new relay for around $20USD this one was brand new
and lasted only a day (it replaced an old one that had lasted 30-
yrs!) I'm not sure if that says the quality is bad, or my car's
headlight circuit is at fault. The HI circuit was upped to 16A fuses
by the previous owner to accomodate Halogen lights. I know the wiring
can handle the current, but maybe the components can't?
Any suggestions for replacing the resistor? The original was very
small - about 5mm long and 2mm in dia. What should the rating be?
Would it help if I clipped the resistor and measured the current
through the coil? Could I replace it w/ a diode (1A, 50v)?
AshMan40
I am trying to repair a 12v latching relay for my Volkswagen Beetle
(~1975). It controls the dimming of the headlights (hi/lo).
The trigger is a momentary ground signal (S) which actuates the coil.
The arm that the coil pulls on has a plunger which toggles a rather
complicated see-saw arm which moves a contact between posts 56a &
56b. Also attached to the arm is a contact which connects to both
outputs (56a & 56b) while the arm is being pulled (I can actually only
see where it connects to terminal 56b on the actual relay). The
diagram may be a bit off since only one of the outputs is "hot" during
actual operation.
The below diagram came from the relay casing. Here is a pic w/ the
circuit diagram screened on the outside of the casing:
http://www2.cip1.com/PhotoGallery.asp?ProductCode=VWC-111-941-583
I've added all the terminal labels in parentheis.
The BAT terminal has constant 12v(+). The IGN terminal has 12v(+)
when both the ignition and the headlight switch are ON. The GRD is
connected to the momentary switch on the turn signal (I've confirmed
it grounds when pressed). The 56a & 56b circuits power the HI/LO beam
circuits, respectively. These are fused after this relay which means
this relay must flow all the current for the headlights.
I believe the mark on the contact that swings between the two outputs
indicates it is a latching contact which stays closed to one of the
outputs until the next activation of the coil.
The extra "swinging" contact to the very right of the diagram would
seem to apply power to both outputs for the brief time that the coil
is energized. The result is that you can dim the headlights w/o the
IGN being on and the headlights will momentarily light up.
The HI circuit is fused w/ two 16A fuses in parallel (total 32A), one
for each headlight. The LO is fused w/ two 8A fuses in parallel
(total 16A).
+-----------------------+
IGN | |
+(56)------|-------------+ |
| | |
BAT | | |
+(30)>-----+-------+ | |
| | + +
| | \ \
R? COIL=====\====<====\
| | \ \
MOM | | / \
GND(S)>----+-------+ + \+ + \
| | |
+-----+---+
| |
(56a) (56b)
HI LO
My problem appears to be the resistor located in parallel w/ the
coil. It is obviously burnt out on my relay. It looks like it
"popped". It is mostly black and I cannot make out the colored
stripes to determine the rating.
I'm assuming the resistor was protecting the coil. If it were to burn
out, wouldn't the coil then take the full current/voltage? I haven't
taken the relay apart enough to test the coil separately, but wired
normally it wasn't activating (which is why I opened up the relay).
While I could buy a new relay for around $20USD this one was brand new
and lasted only a day (it replaced an old one that had lasted 30-
yrs!) I'm not sure if that says the quality is bad, or my car's
headlight circuit is at fault. The HI circuit was upped to 16A fuses
by the previous owner to accomodate Halogen lights. I know the wiring
can handle the current, but maybe the components can't?
Any suggestions for replacing the resistor? The original was very
small - about 5mm long and 2mm in dia. What should the rating be?
Would it help if I clipped the resistor and measured the current
through the coil? Could I replace it w/ a diode (1A, 50v)?
AshMan40
