EM40 Fiat Interface Unit

EM40 Fiat Interface Unit


Overview

The EM40 is an interface between the Fiat 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 has a marker lights output and passes all signals from the Fiat base signal so they can be used by other systems ( door lock/unlock, ignition on, engine running).

It was used in all Auto-Trail Fiat motorhomes up to 2021.  In 2022 the EM40 is fitted in models with a small fridge/freezer;  In models fitted with a large fridge/freezer the EM41 interface fuse box is fitted.

It is used in all Auto-Sleepers Fiat based motorhomes.  In Mercedes based motorhomes the EM45 is used, see here for more details:  EM45 Mercedes Interface Unit


Fuse Allocation


FUSE      RATING        USAGE

Fuse 1      20            Vehicle Battery              See Note1 below.
Fuse 2      20A             Towing Permanent
Fuse 3      5A                Markers
Fuse 4                           Spare
Fuse 5      20A             Fridge D+
Fuse 6      20A             Towing D+
Fuse 7      20A             Fridge Permanent
Fuse 8                           Spare

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/VLM5/VLM7 Tow & rear lights supplies WHITE MOULDING
1 Tow Ground Not Currently Used
2 Tow + Yellow
3 Tow D+ Red
FIAT 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/White









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