EM45 Mercedes Interface Unit
Overview
The EM45 is an interface between the Mercedes base vehicle and the habitation electrics, and is used in conjunction with an EC500 or EC700 power supply system.
The unit provides fused outputs for a the 12V fridge, vehicle battery supply and tow bar. It also passes all signals from the Mercedes base signal so they can be used by other systems ( door lock/unlock, ignition on, engine running).
This unit is a variant of the EM40, and is identical in size and connectivity, so the EM40 connection diagram has been attached.
The only difference between the EM40 and the EM45 is a buffering circuit to isolate the low power door lock & unlock signals available in the Mercedes vehicle from the high current load door lock fitted to the habitation door.
Fuse Allocation
FUSE RATING USAGE
Fuse 1 20A Vehicle Battery See Note1 below.
Fuse 2 20A Towing Permanent
Fuse 3 5A Markers
Fuse 4 5A Door Lock
Fuse 5 20A Fridge D+
Fuse 6 20A Towing D+
Fuse 7 20A Fridge Permanent
Note 1. In Auto-Sleepers vehicles factory witted with a lithium battery Fuse 1 is rated at 25A
Use only good quality fuses and DO NOT replace any fuse with one of a higher value than stated in the list above.
Connectivity
| CONNECTOR / PIN | FUNCTION | COLOUR / CABLE COLOUR | ||
| VB OUT | Vehicle battery out | WHITE MOULDING | ||
| 1 | Battery + | Brown/Green | ||
| 2 | Battery + | Brown/Green | ||
| 3 | Battery Ground | White/Orange | ||
| 4 | Battery Ground | White/Orange | ||
| VB IN | Vehicle battery in | BLACK MOULDING | ||
| 1 | Battery + | Red | ||
| 2 | Battery + | Red | ||
| 3 | Battery Ground | Black | ||
| 4 | Battery Ground | Black | ||
| FRIDGE OUT | Fridge power supply | GREEN MOULDING | ||
| 1 | Fridge Permanent | Not Currently Used | ||
| 2 | Fridge Permanent | Not Currently Used | ||
| 3 | Fridge D+ | Red/Yellow | ||
| 4 | Fridge D+ | Red/Yellow | ||
| FRIDGE OUT | Fridge power supply | BLACK MOULDING | ||
| 1 | Low D+ | Orange/Yellow | ||
| 2 | not used | |||
| 3 | Fridge Ground | White/Black | ||
| 4 | Fridge Ground | White/Black | ||
| TOWING | Tow & rear lights supplies | WHITE MOULDING | ||
| 1 | Tow Ground | Not Currently Used | ||
| 2 | Tow + | Yellow | ||
| 3 | Tow D+ | Red | ||
| VEHICLE IN | Signal inputs | RED MOULDING | ||
| 1 | not used | |||
| 2 | Marker light signal | Purple | ||
| 3 | Unlock | Black/Red | ||
| 4 | Lock | Red | ||
| 5 | Ignition (+12V) | Blue | ||
| 6 | Engine run (-ve) | Brown/White | ||
| TO PSU | user circuits | WHITE MOULDING | ||
| 1 | Low D+ | Orange/Yellow | ||
| 2 | Marker Light Power | Yellow/Black | ||
| 3 | Unlock | White | ||
| 4 | Lock | Green | ||
| 5 | Ignition (+12V) | Blue | ||
| 6 | Engine Run (-ve) | Brown/Whit+D18:H52e |