What it does
Everything the ECU controls depends on steady supply voltage. Injector opening time, coil charge and pump speed all change when voltage sags. This function lets the Elite warn the driver with a dash light when voltage falls too low, flag problems in ESP, and log a trouble code for sudden drops or spikes.
Setting it up
| Tab | Setting | What it does |
|---|---|---|
| Wiring | Output | The wire that drives the warning light, usually a DPO or a stepper output |
| Wiring | Active State | Low (default) grounds the wire when the light should be on. High inverts it, grounding the wire when the light should be off |
| Display | Warning Minimum / Maximum | Battery voltage readouts in ESP flash red below or above these values |
| Diagnostics | Operating Min | Catches a sudden voltage drop and sets DTC P0562 (disabled by default) |
| Diagnostics | Operating Max | Catches a sudden voltage spike and sets DTC P0563 (disabled by default) |
| Battery Light | On Value | The light comes on when voltage falls below this |
Most dash lamps are fed 12V and switched to ground, which is exactly what Low active state does, so leave it at the default unless your light or relay needs the opposite. The ECU output switches to ground, so don't feed a high-current bulb straight through it; use an LED or a relay.
Our approach
Log battery voltage with the engine running and the car's normal electrical loads on, and set the battery light's On Value comfortably below that, so it only comes on for a real charging problem. The Operating Min and Max codes can also be given a DTC severity if Engine Protection is enabled, which is worth doing on a race car where a charging failure mid-session could leave the engine running lean on a tired fuel pump.
If the light comes on, check alternator output and grounds before blaming the ECU. Our ECU grounding guide covers the most common cause of odd voltage readings, and alternator control is worth a look if the Elite runs your alternator.
