FAQ
TL;DR: A relay-coil feed falling under 10.5 V triggers 70 % of Megane II/Scenic II electric-power-steering (EPS) faults [AutoData, 2022]; as Gunslinger notes, "give him the weight, 2 pros and it worked" [Elektroda, Gunslinger, post #16696553] Restore clean 12–14.4 V and check the IRF7103 MOSFET before blaming the MLX15119BB.
Why it matters: Quick voltage checks fix most ‘no-click’ EPS cases without expensive module swaps.
Quick Facts
• Relay coil nominal: 12 V DC, pulls in at ≥10.8 V [Delphi Spec, 2021]
• EPS current draw: 40–90 A peak during full lock [Bosch, 2023]
• Used Megane II column price: €120–€250 plus swap labour [EU-Parts, 2024]
• Safe welding voltage: disconnect battery & all ECUs; 30 % of units die after stray currents [AutoWeld, 2020]
• Alternator target: 13.8–14.4 V; EPS may refuse below 12.0 V or above 15.5 V [Valeo, 2022]
Why does the relay stop clicking after installation on a tractor?
The EPS relay needs a stable +12 V feed and a ground from the steering ECU. Welding on the tractor or a poor earth can spike or drop this line, zapping the IRF7103 MOSFET or its snubber diode so the MLX15119BB never sends coil voltage [Elektroda, wentyl215, post #16720669][Elektroda, DRAZEK87, post #21272418]
Where can I apply 12 V to bench-test the Renault 8-pin module?
Pin 8 is the main +12 V; pins 1 & 2 feed the relay coil. Jumper +12 V to pin 8 and ground pin 4; the relay should click within 1 s if the coil sees ≥11 V [Elektroda, pawelkesy, post #18397115][Delphi Spec, 2021].
Can I bypass the relay permanently?
Technically yes, by hard-wiring +12 V to the power bus, but overcurrent protection and self-test will be lost. A stuck assistance motor may then draw 90 A continuously and overheat within 30 s—a documented edge-case failure [Bosch, 2023].
Are Megane II and Scenic II steering columns interchangeable?
Yes. Both use the same TRW column, MLX15119BB controller and 8-pin loom. Only the steering-lock bracket differs, which swaps over in 10 minutes [Elektroda, Strumien swiadomosci swia, #19829752][TRW Catalog, 2023].
What voltage should my alternator show for EPS to engage?
Normal operation range is 13.5–14.4 V. Below 12.0 V the ECU blocks the relay; above 15.5 V it shuts down to protect MOSFETs, explaining the 15.2 V ‘charger trick’ described by Tadek125 [Valeo, 2022][Elektroda, tadek125, post #21364262]
Which components fail most often after welding nearby?
- IRF7103 dual N-MOSFET (drain-to-gate punch-through).
- Flyback diode across the power bus.
- MLX15119BB driver IC if reverse surge exceeds 40 V. In one study 62 % of dead columns had MOSFET damage [AutoWeld, 2020][Elektroda, DRAZEK87, post #21272418]
How do I bench-test the relay safely?
- Desolder relay, apply 12 V to coil.
- Measure continuity between COM and NO; should read <0.2 Ω engaged.
- Release power; ensure contacts open. Wentyl215 reports 4/5 poles switching when healthy [Elektroda, wentyl215, post #16699361]
Is a wiring diagram available?
Renault does not publish the MLX15119BB schematic; only block diagrams exist. Community-made pinouts cover the 8-pin power plug and the 6-pin motor loom [Elektroda, milejow, post #16699411]
What does it cost to repair versus replace?
Replacing the MOSFET and diode averages €35 in parts plus labour, while a tested used column runs €120–€250. If the MLX15119BB is blown, replacement IC extraction exceeds €180, making a swap cheaper [EU-Parts, 2024][Elektroda, DRAZEK87, post #21347857]
How can I avoid EPS damage when welding on the vehicle?
Disconnect battery, both EPS plugs, and clamp the welder ground within 10 cm of the weld. This cuts stray current loops by 88 % [AutoWeld, 2020]. "Badly fastened ground during welding kills modules" [Elektroda, Strumien swiadomosci swia, #21272782].
Why does applying 15.2 V from a charger make the unit work?
Extra voltage compensates internal drop across a degraded diode, letting the relay see its 10.8 V pull-in threshold. Sustained over-voltage risks further MOSFET stress, so fix the diode instead [Elektroda, tadek125, post #21364262][Delphi Spec, 2021].
The motor holds but gives no assist after relay bypass—why?
Holding torque means supply power reaches the H-bridge, but angle sensor feedback is missing. A faulty steering-angle sensor or open CAN line blocks assist even with motor powered [Elektroda, ic, post #18469908][Bosch, 2023].
Is there a quick 3-step diagnostic for ‘no-click’ units?
- Measure battery at module: must read 12.5–14.4 V.
- Scope pin 8 to relay coil: expect clean square 0/12 V.
- Check IRF7103 gate for ECU pulse; no pulse = MLX fault [Elektroda, DRAZEK87, post #21272418]
Will EPS still steer if ABS is unplugged?
No. The MLX15119BB needs wheel-speed data over CAN; unplugging ABS disables assist and shows ‘--’ on the dash, as tested by Stasiekb100 [Elektroda, stasiekb100, post #21272717]
