The StoneRidge fault (the Bluetooth communication hangs) is cleared by powering down the vehicle: the supply is removed for a short time, then restored. On most vehicles this means switching off the main battery switch — but an average driver often does not know where it is. This page fills that gap: it shows how to recognise and where to find the main switch, by brand and vehicle type.

The data comes from publicly available manufacturer operating and emergency-response manuals. Where there is no confirmed data we deliberately give no specific location — there the recognition guide leads to the goal.

⚠️ Most important: the main switch does not always cut the tachograph supply

The Mercedes Actros factory towing manual states literally, about the battery disconnect switch:

„All consumers are disconnected from the battery, with the exception of the tachograph." (Mercedes-Benz Actros 963, Towing and Recovery)

So on an Actros, switching off the main switch alone does not fix the fault — the tachograph keeps receiving power, and the battery terminal is needed. There is a legal reason: the tachograph must record even with the vehicle stationary, so some manufacturers wire the tachograph before the main switch. There is no public, complete list of which vehicles are like this — so the same check applies to every vehicle.

The check on every vehicle

After switching off the main switch, look at the tachograph display:

what you see	what it means	what to do
the display goes dark	the main switch has cut the supply	wait 30 seconds, switch back on — done
the display stays lit	the tachograph is wired BEFORE the main switch	the main switch is not enough → battery terminal

This prevents the driver switching off the main switch, nothing happening, and believing they were given bad advice.

What are you looking for? — recognising the main switch

The shape is standard regardless of manufacturer, so it is worth starting here.

The dashboard / in-cab switch

a push-button or rocker switch on the lower part of the dashboard, on the centre console, or on the switch panel to the right of the driver
typically marked with a battery symbol: a horizontal rectangle with + and − signs, sometimes a lightning symbol
often an indicator LED shows the switched-off state
it is not next to the ignition key and not among the lighting switches

Important relationship (DAF factory data): if the vehicle has an electronic main switch, then there is also an in-cab switch. If the main switch is mechanical, there is a switch only outside the cab. So if there is no button in the cab, you must look outside.

The switch at the battery box (outside)

type	what it looks like	how it works
red turn knob	a red wheel or knob about 6–8 cm across	a quarter turn (90°)
red lever / switch lever	a long red latch	pull down, pull out or turn up
key isolator	a red body with a removable key or handle	turn or pull out the key

The switch may be under the box lid, or behind a small flap / openable cover on the side of the box. The lid or the area next to the switch typically has a battery or lightning sticker.

How to find it in a minute

Stand at the driver-side door and scan along the chassis frame towards the rear of the vehicle:

what you see	what it is	look here?
a square box with a flat lid, 1–2 snap latches or a strap; often also serves as a step	battery box	yes
a large cylinder or rounded tank with a fuel cap	fuel tank	no
a smaller tank with a blue cap	AdBlue tank	no
several horizontal cylinders side by side	air tanks	no

Step tip: on many trucks the battery box lid is also the second step. If the driver steps on a square box when climbing in, they are most likely standing on what they are looking for.

⚠️ Not always behind the cab! On the MAN TGX/TGS and the Renault T High the battery box is at the rear of the vehicle, and on DAF and Volvo it can also be at the rear, inside the chassis frame. If there is no square box behind the cab, walk to the rear of the vehicle.

Heavy trucks — by brand

Scania (L / P / G / R / S)

External switch behind the cab, on the LEFT side, at the battery box. Typically red.
Alternatively a dashboard switch — the design depends on the vehicle configuration.

Source: Scania factory emergency information (Product information for the emergency services). Confidence: high.

Volvo (FH / FM / FL)

The battery box is on the left-hand chassis side member, or inside the rear cross member.
The main switch, if present, is at the battery box: on the driver side, above the batteries, a large red turn switch in the compartment.
Not every Volvo has a main switch — it depends on the order. Volvo's own emergency guide therefore marks disconnecting the cable as the reliable method.

Source: Volvo FH Service Information (factory) + Volvo FM Driver's Handbook. Confidence: high for the box location, medium for the switch type.

Mercedes Actros / Arocs / Atego

The switch is under a cover: lift the cover, then pull out or turn up the switch lever. To switch back: press the cover down until it latches.
The battery box is on the chassis frame; on tractor units it may also be at the rear.
🔴 KEY: according to the factory manual, the main switch does NOT disconnect the tachograph. On an Actros, therefore, the battery terminal is needed.
The factory warning states that operating the switch disables the power steering, lighting and ABS — so only with the vehicle stationary.

Source: Mercedes-Benz Actros 963, Towing and Recovery (factory). Confidence: high.

MAN (TGX / TGS / TGL / TGM)

The main switch is in the battery box, and the box is at the REAR of the vehicle.
Access: open the two locking catches, then pull the box lid sideways.
The factory operator manual knows two types of main switch: mechanical and electrical.

Source: MAN TGX Operator Manual + MAN Rescue Guide Truck (factory). Confidence: high.

DAF (XF / CF / XG / XD / LF)

The batteries are on the left or right of the chassis frame, or at the rear, inside the chassis. Often under the driver-side step.
With an electronic main switch: the switch is near the battery pack, and there is also a switch on the cab centre console.
With a mechanical main switch: there is a switch only outside the cab.

Source: DAF Emergency Response Guide XF Euro 6 (factory) + DAF LF Emergency User Manual. Confidence: high.

Iveco (S-Way / Stralis / Eurocargo)

The battery box is on the chassis frame, the main switch at the battery box.
On the Stralis the remote switch is on the left side of the vehicle, near the batteries.

Source: Iveco electrical system documentation. Confidence: medium — no public factory rescue sheet was found.

Renault T / C / K / D

On the T High the batteries are in the rear overhang.
There is a battery-disconnect remote switch; the circuit automatically goes to standby.
Physical access: unscrew the locking knob, remove the cover, then disconnect the negative cable.
On the ADR version the main switch is a physical circuit break that opens the ADR relays and disconnects the 12 V batteries.

Source: Renault Trucks T High Driver's Manual + Renault Trucks Emergency Response Guide (factory). Confidence: high.

Medium trucks (3.5–12 tonnes)

Mercedes Atego · MAN TGL/TGM · Volvo FL/FE · DAF LF · Iveco Eurocargo · Renault D. The same principle, with two differences:

the battery box is lower, often directly under or behind the driver step
on many medium models there is no cab-controlled main switch — only the manual isolator at the battery box

If the driver finds no switch in the cab on a medium truck, that is not a fault (with a mechanical main switch there is no in-cab switch).

Asian and Turkish manufacturers (Isuzu N/F · Mitsubishi Fuso Canter · Hino · Ford Trucks F-Max): we give no specific location, as we have no confirmed data — here the recognition guide leads to the goal.

Light commercial vehicles 2.5–3.5 tonnes

Sprinter · Crafter · Transit · Daily · Master · Trafic · Ducato · Boxer · Jumper · Movano · Vivaro · Vito · Transporter and similar. These generally have no factory main switch → powering down means removing the battery terminal.

⚠️ The most common mistake: there are two batteries. Many vans have a starter battery and an auxiliary (leisure) battery. The tachograph is on the starter battery. If the driver removes the auxiliary terminal, nothing happens — find the one to which the thick starter cable runs.

Three places, in this order:

Under the seat. On the Mercedes Sprinter the starter battery is under the driver seat, not in the engine bay: the front-left floor cover and a separate battery cover must be removed. The auxiliary battery, if present, is typically under the passenger seat.
In the engine bay — the traditional place, usually on one side.
In an external battery box on the chassis — on chassis-cab versions (flatbed, box body) the van behaves like a small truck.

Quick decision: open the bonnet. If you do not see the battery, it is under the seat or in an external box.

Buses

The batteries are in an external side compartment opened from outside, typically on the right side (kerb side), above the wheel arch, at the level of the driven axle. The compartment door typically has a lightning symbol or a „BATTERY" label. The main switch is in this compartment.

On the Setra the battery isolator is in the right-side battery compartment, above the driven-axle wheel arch. (Source: Setra factory manual. Confidence: high.)

The same principle: Mercedes Tourismo / Citaro / Intouro / Conecto · Scania Touring / Irizar · MAN Lion's Coach / Lion's City · Neoplan · Volvo 9700 / 9900 · Iveco Crossway / Evadys · Solaris Urbino · VDL · Van Hool · Temsa · Otokar · Karsan · BYD. (No per-model confirmed data — finding the compartment is the practical route.)

Three things to know on a bus:

The battery compartment is usually locked (square or triangular key), and the driver often does not have the key. In that case the task belongs to the depot, workshop or traffic service — this is not a failure.
The cab „battery" rocker switch is not always a main switch — on many buses it only switches a sub-circuit. Here too the display check decides.
The exact compartment side and height varies by model.

Electric commercial vehicles

eActros · Volvo FH/FM/FL Electric · Scania BEV · MAN eTGX/eTGS · DAF XD/XF Electric · Renault E-Tech · Iveco eDaily · Mercedes eSprinter · Ford E-Transit · electric buses. These have two separate electrical systems:

system	what it is for	is the tachograph on it?
low-voltage (24 V / 12 V)	lighting, dashboard, tachograph	yes
high-voltage (HV) drive system	drive motor, traction battery	no

⛔ The driver must never touch the high-voltage system. The HV service disconnect is only for trained specialists. It is life-threatening.

The tachograph is on the low-voltage system, so look for its main switch or battery terminal — in the same place as on the diesel versions.

On an electric bus the large battery on the roof and at the rear is the traction battery — not the one we are looking for. The cab emergency switch is the emergency disconnect of the high-voltage system, not for this purpose.

The correct order for removing the battery terminal

The procedure per the DAF factory rescue manual:

Ignition off.
All electrical consumers off.
Battery cover off.
First disconnect the NEGATIVE (−) terminal.
Then the positive (+) terminal.
Secure the cables so they cannot touch the terminals.

When reconnecting, reverse order: first positive, then negative.

If you cannot find it: there is no need to solve it at the roadside

This fault does not block your work and is not urgent. Every other tachograph function works correctly — it still records driving time, rest and all events. Only the Bluetooth download does not start.

What you can use in the meantime: USB-C card reader (Android), Bluetooth card reader (iPhone/iPad), front-panel downloader.

Next time you reach a garage or workshop, ask for this: „Please power down the vehicle, then restore the power."

That is enough — the mechanic knows what to do and knows where the given vehicle's main switch is. The operation takes a few minutes and the vehicle does not need to be taken apart.

On an electric vehicle, if the driver is unsure which system they are seeing: this is the recommended route — do not attempt it yourself.

Safety and legal warning

Power down only when stationary. The factory manuals specifically point out: operating the main switch can disable the power steering, lighting and ABS.

The tachograph records a power interruption as an event. This is not in itself an infringement if the vehicle was stationary and the operation was justified — but the event will be visible in the downloaded data and may require an explanation during an inspection. It is worth noting when and why it happened.

The solution chain is closed: main switch → if absent or not enough, battery terminal → if neither works: service or workshop. There is no fourth route.

Powering down the vehicle — where is the main switch?