FAQ
TL;DR: On a Trafic II, 14.4 V vs 12.8 V readings flag intermittent alternator excitation; “it showed 14.4 Volts” then none. [Elektroda, leon55, post #16800963]
Quick Facts
- Typical charging voltage observed: 14.5–13.8 V after driving/restarts. [Elektroda, leon55, post #16842862]
- Charge lamp may not light until system drops near 10 V (edge case). [Elektroda, andrzej20001, post #16801354]
- Common weak point: Valeo rotor/coil looseness causing breaks. [Elektroda, robokop, post #16801721]
- Typical alternator rating on some trims: approx. 110–120 A. [Elektroda, andrzej20001, post #16802437]
- Final fix in thread: alternator regulator replacement resolved charging. [Elektroda, leon55, post #18010241]
How do I quickly diagnose a no‑charge condition on a Renault Trafic II (2009)?
With ignition ON, unplug the alternator control plug and ground the indicator wire. The charge lamp should light. If it does, the cluster and wiring can drive the alternator; the alternator needs repair. If it doesn’t, trace the lamp circuit and connectors toward the fuse box. [Elektroda, milejow, post #16802546]
What battery voltage should I see when it is charging correctly?
Expect mid‑14 V right after start, tapering toward high‑13 V as the system warms or load changes. In-thread measurements showed 14.5–13.8 V after driving and restarts. Values stuck near 12.6–12.8 V with engine running indicate no charge. [Elektroda, leon55, post #16842862]
Why won’t the battery light come on and the alternator won’t start charging?
If the charge indicator does not light, the alternator field may not be excited. Inspect the small wires at the alternator for breaks and confirm the alternator type/pins. A non‑COM regulator still needs that lamp feed to kick in. [Elektroda, nikusert, post #16801308]
What commonly fails inside the Valeo alternator on this van?
Forum experts note the rotor winding gets damaged by a loose internal carcass, leading to intermittent or lost excitation. “The loose carcass inside breaks it.” That failure mimics bad wiring or a weak lamp circuit. Bench inspection confirms the fault. [Elektroda, robokop, post #16801721]
Could worn brushes or a faulty regulator cause intermittent charging?
Yes. Short brushes or a failing regulator produce on‑off charging, normal voltage one start and no charge the next. Inspect and replace the regulator/brush pack together when wear is evident. This simple service often restores stable voltage. [Elektroda, zibi581, post #16801605]
What ultimately fixed the charging issue in this thread?
Replacing the alternator regulator solved the problem. After fitting a new regulator, the system charged normally and the warning behaviors disappeared. This confirms the regulator as the root cause in that case. [Elektroda, leon55, post #18010241]
How many amps is the Renault Trafic II alternator?
Typical fitments include approximately 110–120 A units, depending on engine and equipment. This rating supports base electrical loads and moderate accessories. Higher-output versions may exist on other trims, but 110–120 A is a common range. [Elektroda, andrzej20001, post #16802437]
How do I test the charge indicator (D+ lamp) from the alternator plug?
Unplug the alternator. With ignition ON, ground the indicator wire from the harness. The battery lamp should illuminate. If it lights, the cluster and wiring are OK and the alternator is suspect. If not, trace the circuit toward the fuse/connector block. [Elektroda, milejow, post #16802546]
I measure drops on the alternator control wires (orange ~1 V lower, white ~0.5 V). Is that a red flag?
Yes. Those drops point to resistance in the small‑signal wiring or corroded joints. Track the harness and inspect connectors near the front lamp/fuse box area. Any green corrosion or broken strands will cripple the excitation signal. Repair restores lamp and charge. [Elektroda, leon55, post #16812289]
Where are hidden connectors that often corrode on the Trafic II?
Behind the driver-side front lamp, below the fuse box, there is a connector where the cluster’s charge-lamp wire joins the alternator lead. In the thread, the white wire was green and crumbled; soldering restored lamp function and charging. [Elektroda, leon55, post #16842862]
After a long drive, my charging voltage falls from 14.5 V to about 13.8 V. Is that normal?
Yes. The observed behavior was 14.5 V initially, tapering to ~13.8 V with heat and lower demand. That is expected with temperature-compensated regulators. If it later sticks near battery voltage, diagnose excitation wiring or the regulator. [Elektroda, leon55, post #16842862]
At what low system voltage does the battery lamp finally illuminate?
In this discussion, an expert noted the indicator will light around 10 V. That is an edge-case behavior and means you might not see the lamp until the system is already very low. Don’t rely solely on the lamp. [Elektroda, andrzej20001, post #16801354]
What if the alternator fuse is fine but the van still doesn’t charge?
A good main fuse doesn’t rule out excitation faults. The OP had a good fuse, intermittent 14.4 V, then only 12.8 V. The fix came from repairing the small control wire path and replacing the regulator. Check both before swapping the alternator. [Elektroda, leon55, post #16800963]
Is it safe to drive a long distance with intermittent charging?
It’s risky. The OP managed about 100 km while voltages fluctuated between 14.5 V and 13.8 V after restarts. That can strand you if excitation fails. Address wiring corrosion and the regulator before planning longer trips. [Elektroda, leon55, post #16842862]
Can I fix this at home? Give me a simple 3-step how‑to.
- With ignition ON, ground the alternator’s lamp wire; confirm the dash lamp lights.
- Inspect and repair the connector near the driver-side headlamp/fuse box for green corrosion.
- If wiring is good, replace the alternator regulator/brush pack. [Elektroda, milejow, post #16802546]
