Professional Electronics Engineer with specialisms in Test and EMC.

Automotive Relays

Similar to the KL15, KL30 etc. wiring codes in Automotive Wiring, Automotive relays have their own nomenclature. Automotive OEMs (manufacturers) such as Citroen, Jaguar Land Rover, Ford and others (I don’t know if Tesla does as well, but I suspect not) use automotive relays. The labelling of which utilises the DIN 72552 convention for labelling the electric terminals in automotive wiring.

5 small 30 A 12 V coil automotive relays, in sockets. with pinout shown on the label on the top
5 small 30 A 12 V coil automotive relays, in sockets. with pinout shown on the label on the top

Small Automotive Relays

This is the pin out for a 1 Form C relay. (1 Form A, and 1 Form B relays have terminals 87a or 87b de-populated).

  • 85 – relay coil -Ve
  • 86 – relay coil +Ve
  • 87 – common contact
  • 87a – normally closed contact
  • 87b – normally open contact

If the relay has a second set of contacts; such as a 2 Form C relay. (2 Form A and 2 Form B relays have terminals 88a or 88b de-populated).

  • 88a – normally closed contact 2
  • 88b – normally open contact 2

Din 72552

Din 72552 covers more than just the terminals of relays, some of the most common labels are listed below:

ContactMeaningNotesOld terminal designation
Ignition System
KL1ignition coil, distributor, low voltage
KL1a, 1bdistributor with two separate circuits
KL2breaker points magneto ignition
KL4coil, distributor, high voltage
KL4a, 4bdistributor with two separate circuits, high voltage
KL7the terminal on the ballast resistor, to the distributor
KL15battery+ from the ignition switchSee also In Automotive Wiring, What is KL?16
KL15afrom ballast resistor to coil and starter motor16
KL15ebattery+ from the ignition switch, also when the starter motor runs
Preheat (Diesel engines)
KL15preheat in+
KL19pre-heat (glow)
KL45starter relay30f, 30h
KL45astarter 1 output30h, 30h I
KL45bstarter 2 output30h II
KL50starter control
KL50astarter control
KL50bstarter control50
KL50cstarter control50 II
KL50dstarter control50b, 50k
KL50estarter control50a
KL50fstarter control50
KL50gstarter control50a
KL50hstarter control50
KL15battery +Ve through the ignition switchSee also In Automotive Wiring, What is KL?16, 54/15
KL30from battery +Ve directSee also In Automotive Wiring, What is KL?30/51
KL30afrom 2nd battery and 12/24 V relay
KL31return to the battery -Ve or direct to groundSee also In Automotive Wiring, What is KL?
KL31areturn to the battery -Ve 12/24 V relay
KL31breturn to the battery -Ve or ground through switch85d
KL31creturn to the battery -Ve 12/24 V relay31, 31a
Electric motors
KL33main terminal (swap of 32 and 33 is possible)30
KL33f2. slow rpm
KL33g3. slow rpm
KL33h4. slow rpm
KL33Lrotation left30L
KL33Rrotation right30R
KL49flasher unit in15, 15+, 15/54, +, +15
KL49aflasher unit out, indicator switch in54L, S, S4
KL49bout 2. flasher circuit
KL49cout 3. flasher circuit
C1st flasher indicator lightK, K1, P
C22nd flasher indicator lightK1, K2, K3, K4
C33rd flasher indicator lightK3, K4
Lindicator lights leftHL, L54, VL
Rindicator lights rightHR, R54, VR
L54lights out, leftSBL
R54lights out rightSBR
AC generator
KL51DC at rectifiers
KL51eas KL51, with a choke coil
KL59AC out, rectifier in, light switch51, 51-, 51a
KL59acharge, rotor out59
Generator, Voltage regulator
KL61charge indicator (charge control light)
B+battery +Ve51, 51B+, B+30, B+51
B-battery -Ve31-
D+dynamo/alternator diode +Ve
D-dynamo/alternator diode -Ve
DFdynamo field
DF1dynamo field 1
DF2dynamo field 2
U, V, WAC three-phase terminals
KL54brake lights
KL55fog lightN
KL56aheadlight high beam and indicator light
KL56blow beamF
KL56dsignal flash
KL57parking lights
KL57aparking lightsP
KL57Lparking lights leftPL
KL57Rparking lights rightPR
KL58licence plate lights, instrument panel
KL58dpanel light dimmer58b
KL58Lparking light58
KL58Rparking light58
Window wiper/washer
KL53wiper motor +Ve in1, 3, 54d, S
KL53alimit stop +Ve54, +2
KL53blimit stop field3, 54e
KL53cwasher pump
KL53estop field1, 2
KL53iwiper motor with a permanent magnet, third brush for high speed
Acoustic warning
KL71beeper inH
KL71abeeper out, low
KL71bbeeper out, high
KL72hazard lights switch
KL85chazard sound on
KL81a1 out
KL81b2 out
KL82lock in
KL82a1st out
KL82b2nd out
KL82z1st in
KL82y2nd in
KL83multi position switch in
KL83aout position 1
KL83bout position 2
KL85relay coil -Veimportant if the relay coil has a flyback diode in parallel
KL86relay coul +Veimportant if the relay coil has a flyback diode in parallel
Relay contacts
KL87common contact30/51
KL87anormally closed contact
KL87bnormally open contact
88common contact 230/51 (relay)
88anormally closed contact 2
88bnormally open contact 2
KL52signal from trailer
KL54gmagnetic valves for trailer brakes
KL75radio, cigarette lighterR
KL77door valves control
Table of Din 72552 terminal designations for common automotive components.

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