How to read this pinout
The Elite 550 uses one 34-pin main connector. Rather than listing the pins in number order, we've grouped them by job, because that's how you'll plan and check a harness. Wire colors use Haltech's codes: L is blue, V is violet, GY is gray and BR is brown. Where a pin shows a function in italics, that's what it's allocated to by default. It isn't locked to that job, and you can reassign it in ESP.
Power and grounds
| Function | Pin | Wire |
|---|---|---|
| +13.8V ECU and injector power | 26 | R/L |
| Battery ground | 10 | B |
| Signal ground (for sensors) | 11 | B/W |
| +5V sensor supply | 9 | O |
Injection and ignition
| Output | Pin | Wire |
|---|---|---|
| Injector 1 | 19 | L |
| Injector 2 | 20 | L/B |
| Injector 3 | 21 | L/BR |
| Injector 4 | 22 | L/R |
| Ignition 1 | 3 | Y/B |
| Ignition 2 | 4 | Y/R |
| Ignition 3 | 5 | Y/O |
| Ignition 4 | 6 | Y/G |
Trigger and home
| Signal | Pin | Wire (cable) |
|---|---|---|
| Trigger + | 31 | Yellow in the gray 4-core |
| Trigger - | 33 | Green in the gray 4-core |
| Home + | 32 | Yellow in the gray/black 4-core |
| Home - | 34 | Green in the gray/black 4-core |
Sensor inputs
| Input | Pin | Wire |
|---|---|---|
| Throttle position sensor | 14 | W |
| Coolant temperature | 30 | V |
| Air temperature | 29 | GY |
| AVI 1, O2 sensor | 2 | GY/Y, shielded |
| AVI 3, MAP sensor | 15 | Y |
| DPI 1 | 12 | GY, shielded |
General outputs
| Output | Pin | Wire |
|---|---|---|
| DPO 1 | 18 | V/B |
| DPO 2 | 1 | V/BR |
| DPO 3 | 23 | V/R |
| DPO 4 | 25 | V/O |
| DPO 5, fuel pump relay | 24 | B/Y |
CAN bus
| Signal | Pin | Wire |
|---|---|---|
| CAN high | 16 | W |
| CAN low | 17 | L |
Pins 7, 8, 13, 27 and 28 are empty on the Elite 550.
Keep sensor grounds on signal ground (pin 11), never on the battery ground or the chassis. Mixing them is one of the most common causes of noisy sensor readings we see on first start-ups.
For the full harness layouts, see the basic and premium universal harness wiring diagrams, and the Elite 550 overview. Working on an Elite 750 instead? Its pinout is in the Elite 750 complete pinout. A connector face diagram is available too: ask us and we'll send it over with advice for your build.
