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LS drive-by-wire pedal & throttle body pinout (Holley harness)
Running a Holley ECU with a GM drive-by-wire throttle? Holley sells two harnesses: the 558-406 for 6-pin throttle bodies and the 558-429 for 8-pin ones. The pedal plugs in the same way on both. Here is every cavity, wire color and ECU pin.
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Still deciding between a Holley and a factory GM computer for drive-by-wire? See the LS swap ECU comparison.
Which harness fits your throttle body
Match the GM part number on your throttle body. Holley calibrated these units for its ECUs, and warns against using ones not on its list.
| GM throttle body | Holley harness |
|---|---|
| 12570790 | 558-406 (6-pin) |
| 12580760 | 558-406 (6-pin) |
| 12605109 | 558-406 (6-pin) |
| 12629992 | 558-406 (6-pin) |
| 12570800 | 558-429 (8-pin) |
| 12580195 | 558-429 (8-pin) |
Approved pedals: GM 10379038 (both harnesses); the 558-406 sheet also lists Holley 145-160 / GM 19417903.
558-406: pedal + 6-pin throttle body
Pedal connector (6-pin)
| Cavity | Circuit | Wire | P3 pin |
|---|---|---|---|
| A | Sensor ground | black/shield | B16 |
| B | Pedal TPS #2 | blue | B2 |
| C | Sensor +5V | orange | B22 |
| D | Sensor ground | black/shield | B16 |
| E | Pedal TPS #1 | yellow | B9 |
| F | Sensor +5V | orange | B22 |
Throttle body connector (6-pin)
| Cavity | Circuit | Wire | P3 pin |
|---|---|---|---|
| A | Force motor 1B | orange | B7 |
| B | Force motor 1A | yellow | B6 |
| C | Sensor ground | black/shield | B1 |
| D | TB TPS #1 | white | B21 |
| E | Sensor +5V | red | B8 |
| F | TB TPS #2 | brown | B15 |
Loose lead: P3 B24, red/white, brake switch (about 8 ft).
558-429: pedal + 8-pin throttle body
Pedal connector (6-pin)
| Cavity | Circuit | Wire | P3 pin |
|---|---|---|---|
| A | Sensor ground | black/shield | B16 |
| B | Pedal TPS #2 | blue | B2 |
| C | Sensor +5V | orange | B22 |
| D | Sensor ground | black/shield | B16 |
| E | Pedal TPS #1 | yellow | B9 |
| F | Sensor +5V | orange | B22 |
Throttle body connector (8-pin)
| Cavity | Circuit | Wire | P3 pin |
|---|---|---|---|
| A | Force motor 1A | yellow | B6 |
| B | Sensor ground | black/shield | B1 |
| C | Force motor 1B | orange | B7 |
| D | Sensor +5V | red | B8 |
| E | Sensor +5V | red | B8 |
| F | TB TPS #2 | brown | B15 |
| G | TB TPS #1 | white | B21 |
| H | Sensor ground | black/shield | B1 |
Loose lead: P3 B24, red/white, brake switch (about 8 ft).
Holley's 558-429 sheet labels P3 B7 "force motor 2A"; the 558-406 sheet calls the same orange wire "force motor 1B". Same pin, same wire.
Before you start the engine
- Wire the brake switch lead (P3 B24) to the +12V side of the brake light switch. With the brake pressed, Holley caps pedal input at 10% and limits fuel flow; this safety input is required.
- Load the drive-by-wire ICF, pick your throttle body from the list, and run a TPS autoset. Without the autoset the ECU injects no fuel.
- Key on, engine off: press the pedal slowly and watch the throttle blade open fully and return to idle before you ever crank it.
If the throttle loses a sensor, it drops to its "limp home" opening, which lets in more air than idle. You'll need more brake to hold the car in gear.
Drive-by-wire questions
- Drive-by-wire vs cable throttle for an LS swap
- Does it matter which drive-by-wire pedal I use with an LS DBW throttle body?
- Which standalone harness company should a first-timer use for a 5.3 DBW / 4L60E swap in a 67 stepside?
- What does the BBK 80mm drive-by-wire throttle body offer for 1999-2005 4.8/5.3/6.0 trucks?
- Are 8-pin and 6-pin drive-by-wire throttle bodies interchangeable?
- What are my options for the accelerator pedal on a drive-by-wire LS swap?
- Which ECU should I run for a swap that might use drive-by-cable or drive-by-wire?
- Is cruise control easier with drive-by-wire on an LS swap?
- What causes a Gen III LS-swap drive-by-wire system to enter limp mode at wide-open throttle with P1125, P2120, and P2125 despite apparently correct pedal and TPS voltages?
- How do you tune for a larger drive-by-wire throttle body without an adapter, and which ETC tables need updating?
More on computers and throttle choices: Tuning an LS or LT.