Wheel Speed Sensor - Modifications

91porsche03

August 16, 1991


Model Group
911C2/C4/T 9
928 S4/GT

Part Identifier Number

9005 9106


Subject: Speedometer Road Speed Signal


ATTENTION: Service Manager/Service Technician

Models Affected: 911 Carrera 2 with manual transmission 911 Carrera 4 and 911 Turbo, Model Year 91 (M) 911 Carrera 2 with Tiptronic transmission from Model Year 90 (L) 928 S4 and 928 GT, Model Year 91 (M)

Concern: Speedometer road speed signal produced by ABS wheel speed sensor.

Figure 1:

Vehicle Information: The road speed signal for the speedometer and several other control units is produced by the left front ABS wheel speed sensor. The reed contact in the transmission was eliminated.

In order to supply the speedometer and several other control units with the same signal frequency as before, a frequency conversion unit (FCU) installed in the central electric board converts 45 ABS road speed signals per wheel revolution into 8 signals per wheel revolution (Figure 1).


Frequency Conversion Unit Location on CEB

911 Carrera 2 and 911 Turbo - R 52
911 Carrera 4 - R 24
928 S4 and 928 GT - XIX

Parts Information: Frequency Conversion Unit Part Numbers:

911 Carrera 2/911 Turbo: 964 618 220 00
911 Carrera 4/928 S4/GT: 964 618 221 00