This is the relay table for a euro 1988 928s4 automatic.

(relays and functions do differ per year I'm afraid)

Relay Part number Function Diagram Picture
I-II 928 615 115 00 double relay rear window heating
III -- not used  
IV 141 951 253 B relay x-contact ignition 12V-40A
 
V 111 953 227 D

928 615 131 00

 

flasher relay

flasher relay trailer coupling

 

VI 928 615 128 00 relay window lifter
VII U 928 618 205 00

928 615 101 01

wiper interval relay
VIII 141 951 253 B relay defroster 12V-40A
IX 928 618 113 01 relay intens. windshield washer
X 141 951 253 B relay fresh air blower 12V-40A
XI 928 618 223 00 interference choke
XII 141 951 253 B relay fanfare 12V-40A
XIII 141 951 253 B

928 615 117 02

relay fog headlamp
XIV 141 951 253 B relay starter 12V-40A
XV 928 618 109 01 relay kick-down
XVI 928 615 203 00 relay ezk ignition ecu incl fuse tester 12V-20A
XVII 928 615 124 01 relay antiblock system
XVIII 944 615 119 00 relay cooling flaps control  
XIX 928 618 111 00 relay headlight washer system
XX 141 951 253 B relay fuel pump 12V-40A
 
XXI 928 618 125 00 relay interior light  
XXII 141 951 253 B relay back-up light  12V-40A
XXIII-XXIV 928 618 107 04

928 618 107 01

relay headlamp combi
XXV 141 951 253 B relay LH-jetronic 12V-40A
XXVI -- not used  
  928 618 225 01 Timer relay interior lights  
  928 618 104 00 Rear wiper relay (placed near wiper motor in the boot)  
  928 618 102 02 Chime  (Belt/light alarm) unit  
  928 637 160 00 Relay Alarm  
  928 618 521 02 Relay seat heating  
  928 615 127 00 Headlight pop up relay of a 1978-1982 928 series, 12V-30A  

A commonly used relay in a 928 is the 53 model. Here is some detailed info.

Parts: Relay
OEM: 141 951 253 B
431 951 253 H
443 951 253 K
8D0 951 253 A
Make: AUDI VOLKSWAGEN
Remarks:
For:Electric fan 40A,12V 4-pole