VW Relay #100 — 7M0951253A / 4H0951253A | X-Contact Load Reduction Relay | Professionally Pulled & Tested

Accessories suddenly dead — blower, wipers, headlights, radio — but the engine runs fine? That’s Relay #100. Skip the dealer price and get a professionally salvaged, tested OEM unit ready to drop in.

Why Buy From V DUB HUB?

• ✅ Professionally salvaged — pulled clean by an experienced VW specialist
• ✅ Inspected & tested — only quality parts leave our warehouse
• ✅ Fraction of dealer cost — same OEM fitment without the VW dealership markup
• ✅ Direct OEM replacement — plug-and-play, no modifications needed

What Is Relay #100?

Relay #100 (OEM part number 7M0951253A, updated to 4H0951253A) is a heavy-duty 12-volt, 40-amp, 4-pin load reduction relay used across Volkswagen, Audi, Seat, and Skoda platforms.

In 1Z, AHU, and ALH TDI diesel engines, it serves as the primary X-Contact / Accessory Power Supply Relay. Here’s what it does:

• When you crank the engine, Relay #100 disconnects high-draw accessories (blower motor, headlights, radio, wipers) so the starter gets full battery power to turn over the high-compression diesel.
• Once the engine fires and the key returns to “On”, the relay clicks shut and restores power to all cabin accessories.

Symptoms of a Failed Relay #100

• Accessories go dead — heater fan, headlights, radio, and wipers stop working even though the engine runs fine
• Intermittent dropouts — cabin electronics cut out randomly while driving, especially over bumps (loose internal contacts)
• Sticking contacts — relay fails “closed,” keeping accessories powered after the key is removed, draining the battery overnight

Quick Diagnostic Tests

• 🔍 Wiper/Blower Test: Turn the key to “On” without starting. Try the windshield wipers and cabin heater fan. If they don’t respond but your dash warning lights are on — Relay #100 is the prime suspect.
• 🔍 Relay #100 vs. Relay #109: Don’t confuse these two. If your engine cranks but won’t start, that’s Relay #109 (Main ECU Power Relay). If the car starts fine but accessories are dead, that’s Relay #100.

Fitment

Compatible with VW, Audi, Seat, and Skoda platforms using the 1Z, AHU, and ALH TDI engine codes, including MK3 and MK4 Golf, Jetta, Passat, and more. Cross-references: 7M0951253A, 4H0951253A.

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