600cc Secondary Fuse Box

Secondary Fuse Box

The 600cc smart fortwo (1998 to 2002) (or city-coupe and city-cabrio as it was called back then) had a ZEE unit under the dash instead of the SAM unit as found on the 700cc fortwo. The ZEE unit didn’t have many fuses or relays so smart added an extra fuse and relay box underneath the nearside seat, under the carpet. It was power and switching for parts of the engine and transmission. Because it controls power to the transmission, it’s one of the reasons you could be experiencing the 3 bar transmission fault.

You don’t have to remove the seat but it does make things easier. You can push the seat forward and work between the gap in the carpet.

You’ll see a long thin black box with 3 connectors.

Held each end with a 10mm plastic nut.

The relays and fuses are protected by a cover…

…which is held in place with 3 clips.

Lever the clips away and remove the top to reveal the relays and fuses.

The lid contains numbers and letters that probably mean something to smart.

Relays & Fuses

Petrol

Relay Number	Function
K1	Fuel Pump
K2	Auto transmission
K3	Main Relay (powers F3, F4, K3)
K4	Intercooler fan
K5	Starter Relay
K6	A/C Compressor

Fuse Number	Function	Rating
F1	Intercooler, AC magnetic clutch	15 Amps
F2	Fuel pump	10 Amps
F3	ECU, Injectors	15 Amps
F4	Tank vent valve, Lambda sensor	10 Amps

Diesel

Relay Number	Function
K1	Fuel Pump
K2	Auto transmission
K3	Main Relay (powers F3, F4, K3)
K4	Intercooler fan
K5	Starter Relay
K6	A/C Compressor

Fuse Number	Function	Rating
F1	Intercooler, AC magnetic clutch	15 Amps
F2	Fuel pump	10 Amps
F3	ECU, Electrical Cut off, Pressure Valve	15 Amps
F4	Glow plug timing control	10 Amps

Electrical Connections

The secondary fuse box has 3 connections and the cover actually labels them as 1, 2 and M.

Wiring

Connector 1

	Wire Colours	Connection	Function
1	Black Pink	ECU Plug 1, Pin 97,	Fuel Pump Relay Control
2	Red Black	Fuel pump	Fuel Pump
3	Red Blue	Primary fuse box fuse 22	Circuit 30, Unfused
4	Red Blue	Primary fuse box fuse 22	Circuit 30, Unfused
5	Blue	ECU Plug 1, Pin 111	Transmission Relay Control
6	Black White	ECU Plug 1, Pin 117	Transmission 1 Supply Voltage
7	Pink Blue	ECU Plug 1, Pin 115	Transmission 2 Supply Voltage

Connector 2

	Wire Colours	Connection	Function
1	Green	Charcoal valve solenoid	Motor Electronics 2
2	White Yellow	ECU Plug 1, Pin 105	Intercooler Relay Control
3	Green Blue	ECU Plug 1, Pin 113	AC Compressor Relay
4	Red Green	Primary fuse box fuse 9	Switched positive, Unfused
5	Yellow	ECU Plug 1, Pin 112	Starter Motor Lockout Relay
6	Red	Battery +	Circuit 30
7	Brown	Earth	Ground
8	Black Yellow	ECU Plug 1, Pin 119	Motor Electronics 1

Connector M

	Wire Colours	Connection	Function
1	Green	Coil pack 1+2+3	Switched Positive, Unfused
2	Green	Injector 1+2+3	Motor Electronics 1
3	Blue	AC compressor	AC Pressure Switch
4	–	–	–
5	Blue	Starter motor trigger	Starter Solenoid Switch
6	Yellow	Intercooler fan	Intercooler Fan
7	White	Lambda sensor Pin 1	Motor Electronics 2

Relays

Petrol

Relay Number	Function
K1	Fuel Pump
K2	Auto transmission
K3	Main Relay (powers F3, F4, K3)
K4	Intercooler fan
K5	Starter Relay
K6	A/C Compressor

Fuse Number	Function	Rating
F1	Intercooler, AC magnetic clutch	15 Amps
F2	Fuel pump	10 Amps
F3	ECU, Injectors	15 Amps
F4	Tank vent valve, Lambda sensor	10 Amps

Diesel

Relay Number	Function
K1	Fuel Pump
K2	Auto transmission
K3	Main Relay (powers F3, F4, K3)
K4	Intercooler fan
K5	Starter Relay
K6	A/C Compressor

Fuse Number	Function	Rating
F1	Intercooler, AC magnetic clutch	15 Amps
F2	Fuel pump	10 Amps
F3	ECU, Electrical Cut off, Pressure Valve	15 Amps
F4	Glow plug timing control	10 Amps