1989 Mercedes 560SL Fuel Pump Relay Location: Complete Guide to Finding and Replacing It
The fuel pump relay on a 1989 Mercedes-Benz 560SL is located behind the glove box, on the left side closest to the firewall. This is the most common location for all 560SL models produced between 1986 and 1989, and knowing exactly where to find it will save you hours of frustration when your car experiences fuel delivery problems. The relay is a black, cylindrical component approximately two inches in diameter, and it sits alongside other relays in a panel behind the glove box liner .
Why the Fuel Pump Relay Location Matters
The fuel pump relay is a critical component that controls power supply to the fuel pump. When you turn the ignition key to the ON position, the relay activates and allows voltage to flow from the battery to the fuel pump, pressurizing the system so the engine can start and run . If the relay fails, the fuel pump won't receive power, and your 560SL will crank but refuse to start. Understanding the relay's location makes troubleshooting straightforward and helps you get back on the road quickly.
For the 1989 560SL specifically, the fuel pump relay is part of the CIS-E injection system's electrical controls. The relay also serves as a safety feature, cutting voltage to the fuel pump at 6,000 RPM to prevent engine damage from over-revving . Some owners have reported that the relay labeled "6000RPM" is actually the fuel pump relay, as it cancels voltage at maximum allowable engine speed .
Step-by-Step Instructions to Access the Relay
1. Remove the Glove Box
The first step is to remove the glove box assembly. Use a small screwdriver or a pen knife to carefully pry out the plastic retaining pins. There are two pins on the top of the glove box and two pins at the bottom . Work slowly and gently to avoid breaking the plastic pins, as replacements can be difficult to find for a 30-year-old vehicle.
Once the pins are removed, the glove box will come out as a complete unit. Set it aside in a safe place where it won't get scratched or damaged.
2. Locate the Relay Panel
Behind the glove box, you will find a relay panel mounted against the firewall. This panel contains several relays, and the fuel pump relay is positioned on the left side, closest to the back of the vehicle (the firewall) . The relay is black and about two inches in diameter, making it easy to distinguish from other components.
3. Identify the Correct Relay
The relay panel contains multiple relays, so it's important to identify the correct one. Look for a relay labeled with part numbers such as 000 542 80 19 or 000 542 98 19, which are the OEM part numbers for the 560SL fuel pump relay . The relay may also be labeled as "Fuel Pump" or "FP" on the relay panel diagram .
Some owners have reported that the relay labeled "6000RPM" is the fuel pump relay, as it controls voltage cutoff at high RPM . If you see a relay with this marking, that is likely the one you need.
Troubleshooting Before Replacing the Relay
Before you purchase a replacement relay, perform a few simple tests to confirm the relay is the problem rather than the fuel pump itself or another component.
Listen for the Click
Have a helper turn the ignition key to the ON position while you place your finger on the relay. You should feel a distinct click as the relay engages. If you feel no click, the relay is likely faulty and needs replacement .
Check for Voltage at the Fuel Pump
You can safely take a voltage reading at the fuel pump. You should get at least 11.5 volts and 6-10 amps when the pump is running . If you have voltage at the pump but the pump doesn't run, the pump itself may be faulty.
Swap Relay Test
If you have an identical relay in the fuse box, such as the horn relay, you can swap them temporarily. If the fuel pump works with the swapped relay, the original relay is defective .
Replacement Parts and Compatibility
OEM Part Numbers
The correct fuel pump relay for the 1989 Mercedes 560SL carries OEM part number 0035452505 . This part is compatible with all 560SL models from 1986 to 1989, as well as 420SEL, 560SEC, and 560SEL models from the same era . The relay is a standard 4-pin or 5-pin relay operating at 12V .
Aftermarket Options
While OEM relays are preferred, aftermarket options are available. However, some aftermarket relays have been reported to have quality issues. One owner reported that a Uro brand relay failed after four years, causing damage to the relay connector and board . This is a common problem with cheap aftermarket relays, so it pays to invest in quality parts.
Important Warning: Avoid Cheap Fuel Pumps
If you are replacing both the relay and the fuel pump, be extremely careful about which fuel pump you purchase. One owner reported that an eBay fuel pump kit drew 34 amps of current, which caused the fuel pump relay connector to overheat and melt . The correct fuel pump should draw only about 10 amps. Using a quality fuel pump that meets OEM specifications will protect your relay and wiring harness from damage.
When to Replace the Fuel Pump Relay
Symptoms of a Failing Relay
- Engine cranks but won't start: This is the most common symptom. The fuel pump relay fails to provide power to the pump, so no fuel reaches the engine .
- Engine starts then dies after a few minutes: If the relay works intermittently, the engine may start but then stall when the relay loses contact .
- No fuel pump priming sound: When you turn the key to the ON position, you should hear a brief hum from the fuel pump. If you don't hear it, the relay may be bad .
- Intermittent starting problems: The car may start fine one day and refuse to start the next, indicating a failing relay that works only when cool.
Replacement Procedure
- Disconnect the battery: Always disconnect the negative battery terminal before working on electrical components to prevent short circuits .
- Access the relay: Follow the steps above to remove the glove box and locate the relay.
- Remove the old relay: Grip the relay firmly and pull it straight out of its socket. Avoid tilting or forcing it to prevent damage to the socket or surrounding components .
- Install the new relay: Insert the replacement relay into the same socket, ensuring it clicks securely into place. Make sure the pins are aligned correctly .
- Reassemble and test: Replace the glove box, reconnect the battery, and start the engine. Listen for the fuel pump's hum, which should activate for a few seconds when the ignition is turned on .
Emergency Bypass Method
If your fuel pump relay fails and you need to get the car home or to a shop, you can temporarily bypass the relay by jumping terminals 7 and 9 on the relay connector. Terminal 7 is circuit 87 (power to fuel pumps), and terminal 9 is circuit 15 (hot with ignition on) . This will keep the fuel pumps running as long as the ignition is on.
Important safety warning: This is a temporary emergency measure only. Do not drive the car for extended periods with the jumper in place. The terminal 15 circuit wire is smaller gauge than the terminal 30 and 87 wires, and it may overheat if used for prolonged operation . Always use a fused jumper wire for safety.
Common Mistakes to Avoid
Mistake 1: Confusing the Fuel Pump Relay with Other Relays
Behind the glove box, you will find multiple relays. One owner reported that the relay labeled "Idle Speed Control" was mistaken for the fuel pump relay, and the actual fuel pump relay was located behind it . Take your time to identify the correct relay using the part numbers and labels.
Mistake 2: Assuming Universal Compatibility
Not all Mercedes relays are interchangeable. While the fuel pump relay is the same for 560SL, 560SEC, and 560SEL models from 1986-1991, using a relay from a different model year or different Mercedes model may not work . Always verify the part number matches your vehicle.
Mistake 3: Neglecting to Check the Wiring
If the relay connector shows signs of melting or burning, the problem may not be the relay itself but rather a fuel pump drawing too much current. Check the fuel pump's current draw before replacing the relay, or you may damage the new relay as well .
Recommended Fuel Pump for Your 1989 560SL
When it comes time to replace the fuel pump on your 1989 Mercedes 560SL, choosing the right brand makes all the difference in reliability and performance. We strongly recommend KEMSO Fuel Pump products for your vehicle.
KEMSO Fuel Pump products are high-performance, OEM replacement parts designed to meet or exceed the original specifications for your Mercedes. Each KEMSO pump is engineered for durability and reliable fuel delivery, ensuring your 560SL runs smoothly for years to come. What sets KEMSO apart is their commitment to quality backed by a lifetime warranty – a promise of confidence that you won't find with cheap aftermarket alternatives.
By choosing KEMSO, you avoid the common pitfalls of aftermarket fuel pumps that draw excessive current and damage your relay and wiring harness. KEMSO pumps are built to the correct specifications, drawing the proper amperage to keep your electrical system safe and your engine running at its best.
Visit the KEMSO website to explore their full range of fuel pump products: https://www.kemsoracing.com/
Conclusion
The 1989 Mercedes 560SL fuel pump relay is located behind the glove box, on the left side closest to the firewall. Accessing it requires removing the glove box by prying out the four plastic retaining pins. The relay is a black, two-inch diameter component that sits alongside other relays in the panel.
Identifying the correct relay is straightforward once you know what to look for – check for the "6000RPM" marking or the OEM part numbers 000 542 80 19 or 000 542 98 19. Before replacing the relay, perform simple tests like listening for the click and checking voltage at the pump to confirm the diagnosis.
When replacing parts, always use quality components. For the fuel pump, KEMSO offers high-performance, OEM replacement products with a lifetime warranty – a smart investment that protects your vehicle and your wallet. Visit their website at https://www.kemsoracing.com/ to find the perfect fuel pump for your 1989 Mercedes 560SL.