Rear Body

This node owns the following devices, starting with the tail-lamp clusters:

Rear Lights

  • Left and Right Rear Indicators (21W) M6 M8
  • Left and Right Tail Lights (5W) M2 M4
  • Left and Right Brake Lights (21W) M9 M10
  • Left and Right Reversing Lights (21W) M16 M17
  • Rear Fog Light (21W) L20

Other devices:

  • Tailgate Switch F5
  • Luggage Compartment Light (5W) W3Fuel Pumps and Float Level
  • Filler Flap Lock
  • Fuel Level Float G
  • Fuel Transfer Pump G23
  • Fuel Pressure Pump G6

Summary of I/O

Input Output
Indicator Left 2A
Tail Light Left 0.5A
Brake Light Left 2A
Reverse Light Left 2A
Reverse Light Right 2A
Brake Light Right 2A
Tail Light Right 0.5A
Indicator Right 2A
Rear Fog 2A
Tailgate Switch – 1 bit Compartment Light 0.5A
Fuel Level – Analog Transfer Pump ?A
Pressure Pump ?A
Filler Flap locked/unlocked 2-bit Flap Lock H-bridge

A total of 18 I/O external to the node. There are further inputs from sensing output driver states to detect short-to-ground or short-to-supply.

It’s high-side FET drives all round except for the fuel tank float level sense and the filler flap actuator which will change from vacuum to electric (H-bridge drive), with positional feedback .

The fuel pumps are fused at 25A for both as stock. Separate fuses for every lamp can provide useful information but don’t improve operational reliability, as the pressure pump should stop when the transfer pump fails, so 1 fuse for both.

Lamps can be fused per cluster. It is more likely that something causing a fuse to blow on one side will not affect the other. If two 5A fuses are used per cluster, then e.g. indicator, tail and fog light can operate off one and reverse and brake light from the another.

A single 5A fuse is then sufficient to run the other loads driven by the node.

Total current drawn via the node is about 40A maximum with fog, brake and tail lights on, tailgate open (compartment light lit) and emergency flashers going while the engine is running. Don’t try to tell me that that doesn’t happen every day! 🙂

Anti-theft immobilization can be implemented by not starting the fuel pump when commanded. Such a command may be physically injected by a rogue node pretending to be the LINbus master, but the message’s signature won’t match that of the trusted LINbus master node.