30/05/2008
The Volvo 940, a true workhorse of Swedish engineering, holds a special place in the hearts of many motorists across the UK and beyond. Produced between 1990 and 1998, this robust vehicle earned a reputation for its reliability, safety, and practicality. However, even the most dependable machines require a bit of understanding when it comes to their inner workings, especially their intricate electrical system. A common area where owners might find themselves scratching their heads is the fuse box, a crucial component that protects your car's vital circuits.
Understanding your Volvo 940's fuses and relays isn't just for mechanics; it's essential knowledge for any owner looking to perform basic maintenance and quick troubleshooting. Whether you're dealing with a dead cigarette lighter, malfunctioning headlights, or a radio that's gone silent, the fuse box is often the first place to look. This detailed guide will walk you through everything you need to know about the Volvo 940's fuse and relay system, including their location, assignments, and how to interpret the diagrams, ensuring your classic Volvo continues to deliver its renowned reliability.
- The Heart of Your Volvo's Electrics: Where to Find the Fuse Box
- Understanding the Volvo 940 Fuse Assignments
- Understanding Your Volvo 940's Relays
- Practical Tips for Electrical Maintenance and Troubleshooting
- Frequently Asked Questions (FAQs)
- What years was the Volvo 940 produced?
- Where is the fuse box located in a Volvo 940?
- Which fuse controls the cigarette lighter in my Volvo 940?
- Why do fuse assignments vary in Volvo 940s?
- How do I know if a fuse is blown?
- Can I use a higher amp fuse if I don't have the correct one?
- What if replacing a fuse doesn't fix the problem?
- Conclusion
The Heart of Your Volvo's Electrics: Where to Find the Fuse Box
Locating the fuse and relay box in your Volvo 940 is the first step towards diagnosing any electrical issues. Volvo thoughtfully placed the main fuse box in a relatively accessible spot within the cabin. You'll find it situated in the middle of the dashboard panel, discreetly positioned behind the ashtray. To gain access to this vital block, the ashtray assembly typically needs to be carefully removed. This design ensures that while the fuses are protected from everyday wear and tear, they are still within reach when needed for inspection or replacement. Always ensure your vehicle is switched off before attempting to access or manipulate any electrical components.
Understanding the Volvo 940 Fuse Assignments
The purpose of fuses can sometimes vary depending on your Volvo 940's specific year of manufacture, its level of electrical equipment, and even the region where it was originally delivered. This variability is due to updates made to the model throughout its production run from 1990 to 1998. Always consult your vehicle's owner's manual for the most precise information, but the following table provides a comprehensive overview of the fuse assignments commonly found in the Volvo 940.
Volvo 940 Fuse Diagram and Assignment Table
| Fuse No. | Amperage | Assignment |
|---|---|---|
| 1 | 25A | Main fuel pump, fuel injection system, ignition system, oxygen sensor heater (B200, B230FT) |
| 2 | 25A | Hazard alarm, headlight flash, central locking, anti-theft alarm |
| 3 | 30A | Power seats, trailer (’93-’95) |
| 4 | 15A | Brake lights, shift lock |
| 5 | 15A | Glove box light, clock, radio, interior light, boot light, open door warning light, powered antenna, vanity mirror, anti-theft alarm |
| 6 | 30A | Electronic Climate Control (ECC), Fan – Climate Control Unit |
| 7 | 15A | Front fog lights, rear fog lights |
| 8 | 30A | Power windows |
| 9 | 15A | Key reminder, seat belt reminder, manual climate control (MCC), A/C relay (’90-’92), warning light (seat belt), turn signals, heated front seats, power windows, shift lock, trailer |
| 10 | 30A | Heated rear window, power sunroof, power and heated mirrors |
| 11 | 15A | Fuel tank priming pump (LH-2.4 MFI), oxygen sensor (HO2S) Heating (B200F, B230FB/FD) |
| 12 | 15A | Reversing lights, cruise control, overdrive (manual transmission), 4th gear disengagement (automatic transmission), lamp failure warning light, anti-theft alarm, exhaust gas temperature sensor (Japan) |
| 13 | 15A | Pulsair – Solenoid Valve, Fuel Valve (Diesel), Preheater (Diesel), EGR (Diesel), Secondary Air Pulse Injection (PAIR), Solenoid (B230FD) |
| 14 | 15A | Power mirrors, cigarette lighter, radio, rear wiper (estate), ambient air temperature sensor |
| 15 | 25A | Horn, windscreen wiper/washer, headlight wiper/washer, power seats |
| 16 | 30A | Heater fan, A/C, electronic climate control (ECC) control module, ECC solenoids |
| 17 | 15A | Left headlight (high beam), high beam indicator |
| 18 | 15A | Right headlight (high beam), front fog lights (Japan) |
| 19 | 15A | Left headlight (low beam), fog lamp relay, beamwidth control |
| 20 | 15A | Right headlight (low beam), beam width adjustment |
| 21 | 15A | Left position lights (front and rear), licence plate light, ashtray light, heater control panel light, heated rear window and sunroof switch light, left instrument panel light, radio light, ambient temperature sensor |
| 22 | 15A | Seat belt illumination, right position lamps (front and rear), centre console compartment illumination, fog lamp relay, seat heating switch illumination, gear selection panel illumination, rear ashtray illumination |
| 23 | 25A | Heated front seats |
| 24 | See notes | ’90–’92: SRS test socket; ’94–’95: ABS (15A) |
| 25 | See notes | ’90-’92: Rear fog lights; ’93–’95: Rear fog lights (USA, CND, Japan), switchable low beam (Nordic, Netherlands, Belgium) |
| 26 | 25A | Radio, Amplifier, CD Changer |
The Cigarette Lighter Conundrum: Fuse 14 to the Rescue
One of the most common reasons owners delve into their fuse box is a non-functional cigarette lighter socket, which is often used for charging mobile phones or powering accessories. For the Volvo 940, the fuse responsible for the operation of the cigarette lighter is Fuse number 14. This 15-amp fuse also protects the power mirrors, radio, rear wiper (on estate models), and the ambient air temperature sensor. If your cigarette lighter isn't working, this is the first fuse you should inspect.
Additional Fuse Considerations: The ABS System
It's important to note that certain Volvo 940 models may have additional fuses located outside the main fuse box. Specifically, on vehicles produced between 1990 and 1993 that are equipped with an anti-lock braking system (ABS), the system is protected by an additional 10-amp fuse. This particular fuse is typically found under the instrument panel, positioned to the left of the steering wheel. Always check this location if you are experiencing ABS-related electrical issues on these specific model years.
Understanding Your Volvo 940's Relays
While fuses protect circuits from overcurrent, relays act as electrical switches, allowing a low-power signal to control a high-power circuit. They are crucial for the operation of various components, from your headlights to your fuel pump. Like fuses, relay assignments can vary by model year and specification. Here’s a general overview of the relays found in your Volvo 940:
Volvo 940 Relay Diagram and Designation Table
| Relay | Designation |
|---|---|
| A | Lamp Warning Sensor |
| B | Seat Belt Reminder/Key Warning |
| C | Intermittent wiper |
| D | Intermittent Wiper (Tailgate – Estate) |
| E | Fuel injection |
| F | Front fog lights |
| G | Headlight flasher |
| H | Exhaust gas temperature sensor (Japan) |
| I | Overdrive |
| J | Overload (power windows/heated seats) |
| K | Headlight |
| L | Central locking |
| M | Rear fog lamp |
| N | High Beam Overload (Except USA, CND) |
| O | – |
| P | – |
| R | – |
| S | – |
Practical Tips for Electrical Maintenance and Troubleshooting
Armed with the knowledge of your Volvo 940's fuse and relay layout, you're better equipped to handle minor electrical hiccups. Here are some practical tips:
- Always Use the Correct Amperage: Never replace a blown fuse with one of a higher amperage rating. Doing so can lead to serious electrical damage, including wiring fires, as it removes the intended protection for the circuit.
- Keep Spares Handy: It's wise to carry a small assortment of spare fuses of various common amperages (e.g., 10A, 15A, 25A, 30A) in your glove box. This can save you from being stranded by a simple blown fuse.
- How to Identify a Blown Fuse: Fuses typically have a small wire or strip inside that melts when overloaded. A visual inspection will usually reveal if this wire is broken. Some fuses also have a small coloured indicator that pops out when blown.
- Replacing a Fuse: Use a plastic fuse puller (often found in the fuse box lid or with your spare fuses) to gently remove the old fuse. Push the new fuse firmly into place.
- If a Fuse Blows Repeatedly: If a particular fuse keeps blowing, it indicates a deeper electrical problem, such as a short circuit or an overloaded component. Do not continue to replace it, as this can cause further damage. It's best to consult a qualified mechanic in such cases.
- Relay Issues: While less common than fuse issues, a faulty relay can also cause component failure. Relays can sometimes be tested by swapping them with an identical, known-good relay from another circuit (if available and safe to do so) or by listening for a click when the circuit is activated.
Frequently Asked Questions (FAQs)
What years was the Volvo 940 produced?
The Volvo 940 was produced for nine years, from 1990 through to 1998. During this period, the model received various updates and refinements.
Where is the fuse box located in a Volvo 940?
The main fuse and relay box in the Volvo 940 is located in the cabin, specifically in the middle of the dashboard panel, directly behind the ashtray. You will need to remove the ashtray to access it.
Which fuse controls the cigarette lighter in my Volvo 940?
The cigarette lighter in your Volvo 940 is protected by Fuse number 14. This is a 15-amp fuse that also serves other components like power mirrors and the radio.
Why do fuse assignments vary in Volvo 940s?
Fuse and relay assignments can differ based on the vehicle's specific year of manufacture, its level of electrical equipment (e.g., optional extras like power seats or climate control), and the region for which the car was originally destined (e.g., USA, Japan, Nordic markets). Volvo implemented updates throughout the 940's production run, leading to these variations.
How do I know if a fuse is blown?
Most fuses are transparent, allowing you to visually inspect the thin metal strip inside. If this strip is broken or melted, the fuse is blown. Some modern fuses also have a small indicator that changes colour or pops out when the fuse has failed.
Can I use a higher amp fuse if I don't have the correct one?
Absolutely not. Using a fuse with a higher amperage than specified can lead to severe electrical damage, including overheating wires, short circuits, and potentially a vehicle fire, as it bypasses the safety mechanism designed to protect the circuit.
What if replacing a fuse doesn't fix the problem?
If you replace a blown fuse and the component still doesn't work, or if the new fuse blows immediately, it indicates a more serious underlying electrical issue. This could be a short circuit in the wiring, a faulty component drawing too much current, or a problem with a relay. In such cases, it's best to consult a professional automotive electrician or mechanic.
Conclusion
Understanding the fuse and relay system of your Volvo 940 is a fundamental aspect of responsible car ownership. While these components are small, their role in protecting your vehicle's complex electrical circuits is immense. By knowing where to find your fuse box, how to interpret the diagrams, and which fuse corresponds to which function, you can confidently diagnose and often resolve minor electrical issues yourself. This knowledge not only saves you time and potential repair costs but also helps maintain the enduring reliability that the Volvo 940 is so well-regarded for. Keep this guide handy, and your classic Volvo will continue to serve you faithfully for many years to come.
If you want to read more articles similar to Volvo 940 Fuses & Relays: Your Electrical Guide, you can visit the Maintenance category.