Try the instructions below the Holden VT/VX service CD. I can't work out how to insert the up and down arrowhead icons in the text below so have just included them as descriptions in quotes. You should know what an arrowhead button looks like.
DIAGNOSTIC MODE OPERATION
To enter the instrument cluster diagnostic mode, press the trip computer switch MODE button down together with the "Up Arrowhead" button while turning the ignition from off to on. Further pressing the MODE button will step through the various instrument cluster information displays.
When the Diagnostic Mode Display is reached, pressing the "Up Arrowhead" button increments the DTC number and related information displayed, while the "Down Arrowhead" button can be used to decrement the DTC number and related information. To exit the instrument cluster diagnostic mode, press both the "Up Arrowhead" button and the "Down Arrorhead" button together.
A DTC is shown on the Diagnostic Mode Display as ‘t NN XY’ , where:
t = diagnostic trouble code (DTC),
NN = the actual DTC number,
X = the history DTC status (H for active and – for inactive), and
Y = the current DTC status (C for active and – for inactive).
In instances where the DTC is disabled due to the particular model configuration the letters nu (not used) appear in the XY position. For example, a vehicle which is not fitted with ABS or ABS/ETC will have DTC 8 shown as ‘t 08 nu’. Similarly, DTC 4, DTC 5 and DTC 6 will appear as not used on a vehicle which is not fitted with LPG.
It is important to note that an open circuit fuel (petrol) gauge sender unit is recognised by the instrument cluster selfdiagnostics as ‘t 00 H C’, whereas the TECH 2 Diagnostic Tool will recognise the same fault as DTC 3.
A DTC may also be cleared from the instrument cluster using the trip computer switches while in the diagnostic mode. With the DTC displayed in the instrument cluster window, press both the "Up Arrow" button and the "Down Arrow" button together for more than 2 seconds. Pressing these buttons for less than 2 seconds will exit the instrument cluster diagnostic mode.
DTC CODE
1 Fuel gauge sender unit — short circuit
2 Fuel gauge sender unit — intermittent
3 Fuel gauge sender unit — open circuit (refer to Note 1)
4 LPG gauge sender unit — open circuit
5 LPG gauge sender unit — short circuit
6 LPG gauge sender unit — intermittent
8 No serial data from ABS – Traction off enable (refer to Note 2)
9 No serial data from BCM
10 No serial data from ECC (refer to Note 3)
11 No serial data from PCM
12 No serial data from SDM
13 No instrument poll from BCM
14 No serial communication
15 No Sub-clock
16 ABS or ABS/ETC fault logged
17 BCM fault logged
18 ECC fault logged
19 PCM fault logged
20 SDM fault logged
21 Trip switch short circuit
22 Trip switch button stuck
24 EE checksum error
25 ROM checksum error
26 Internal fault Yes None
NOTE 1: DTC 3 is recognised by the instrument cluster self-diagnostics as ‘t 00 H C”.
NOTE 2: DTC 8 is not enabled in vehicles fitted with ABS only.
NOTE 3: The ECC EEPROM enable bit is programmed active for the high series vehicles and inactive for the low series vehicles during manufacture.
