The engine at a glance
This is the 90-degree, pushrod 3.8-liter V6 GM used across Buick and Holden models, known in Australia as the Ecotec in later form. The most common home for it is the Holden Commodore from VN through VX.
| Spec | Value |
|---|---|
| Layout | 90-degree V6 |
| Displacement | 3,791 cc (231 ci) |
| Firing order | 1-6-5-4-3-2 |
| Bank numbering (viewed from the driver's seat) | Left bank 1, 3, 5; right bank 2, 4, 6 |
Early vs late: know which one you have
Everything about ECU choice hinges on this split.
- VN to VP: load is measured with a MAP sensor. There's no MAF and no cam sensor. The factory Delco ECU drives the injectors in two groups fired together.
- VR onward: load comes from a MAF, there's a cam position sensor, and the factory Delphi ECU runs sequential injection.
Choosing a Haltech ECU
| ECU | Install type | OEM functions it won't handle | Sequential / direct fire | Auto trans control |
|---|---|---|---|---|
| Platinum Sport GM | Plug-in, VN to VP only | Not suited to VR onward | No | VN to VP |
| Elite 550 | Piggyback | Idle control, A/C, serial body control | No | No |
| Elite 750 | Piggyback | Idle control, serial body control | Yes | No |
| Elite 950 | Piggyback | Idle control, sequential fuel and serial body control on VR onward | No | No |
| Elite 1000 / 1500 | Standalone | Sequential fuel and serial body control on VR onward | No | Yes |
| Elite 2000 / 2500 | Standalone | Serial body control on VR onward | Yes | Yes |
What we'd pick
- VN to VP: these early engines are simple, and the Platinum Sport GM plug-in covers them without extra wiring.
- VR onward, full standalone: an Elite 2000 or Elite 2500. Both run sequential fuel, can drive the coils directly if you ever ditch the DFI module, and handle the factory stepper idle valve.
- VR onward, keeping the factory ECU: an Elite 750 piggyback can take over fuel and ignition while the OEM ECU keeps doing everything else.
Sensor and module pinouts
Crank sensor
One housing, two sensors inside: an 18x signal and a 3x signal. A Haltech uses only one of them. Choose at install time; we use the 18x wherever possible since it gives the ECU more position information per revolution.
| Pin | Function |
|---|---|
| A | 3x signal |
| B | 18x signal |
| C | Signal ground |
| D | 12V+ |
Cam sensor
Hall effect. Not fitted to early VN to VP engines.
| Pin | Function |
|---|---|
| A | Signal |
| B | Signal ground |
| C | 12V+ |
DFI ignition module
| Module pin | Connect to |
|---|---|
| A | Haltech Ignition Output 1 |
| B | DPO1, set as a 5V pull-up, high state (bypass signal) |
| C | No connection |
| D | Haltech Trigger + |
| E | Tachometer |
| F | Haltech Home + |
| G | No Haltech connection (goes to crank sensor 18x) |
| H | No Haltech connection (goes to crank sensor 3x) |
| J | No Haltech connection (goes to cam sensor) |
| K | No connection |
| L | Haltech trigger signal ground |
| M | Crank and cam sensor ground |
| N | Crank and cam sensor power |
| P | 12V+ supply |
Throttle position sensor
Pin A is 5V+, pin B is signal ground and pin C is the signal.
MAP sensor
The factory part is a 1-bar sensor. It reads vacuum up to atmospheric pressure and nothing above, so it's fine for a naturally aspirated engine but useless for boost. If you're adding a turbo or supercharger, change to a sensor with the range you need.
| Pin | Function | Haltech wire |
|---|---|---|
| A | Signal ground | Signal ground (black/white) |
| B | Signal | A spare AVI (AVI-9, yellow) |
| C | 5V+ | 5V+ (orange) |
Calibration file: MAP - GM 1 Bar.cal. Haltech sells the same style of 1 bar GM MAP sensor if yours is tired.
Idle valve
A 4-wire stepper motor. Pins A through D go to Haltech Stepper 4, 3, 2 and 1 in that order. The base maps have the stepper configuration to start from.
Coolant and air temperature sensors
- Coolant: common EV1 connector, not polarity sensitive. Calibration
Temperature - Holden VP V8 Coolant Sensor.cal. - Intake air: Delphi connector where the wire is fed through the housing first, the terminal crimped on, then pulled back to lock. Not polarity sensitive. Calibration
Temperature - Holden VP V8 Air Sensor.cal.
Both calibrations assume the Haltech input's 1k pull-up to 5V is in use.
The DFI module: why it's different
The distributorless ignition (DFI) module on this engine is clever. With no ECU connected, it will still fire every cylinder by timing sparks directly off the 3x crank signal. When an ECU is present, the ECU sends 5V to the module's bypass input. The module then passes the crank signal to the ECU, and the ECU sends back a single timed spark signal that the module distributes to the correct coil.
Because the module handles coil sequencing, the ECU only needs one ignition output, just as if it were driving a distributor. That's why the Haltech's Ignition Mode must be set to Distributor when the DFI module stays in place. If you remove the module and fire the coils directly, you'll need an ECU that supports direct fire and different settings.
If the engine starts and runs but timing won't move when you change the map, the module probably isn't in bypass. Confirm DPO1 is configured as a high-state 5V pull-up and that it reaches module pin B.
Troubleshooting
| Symptom | Usually |
|---|---|
| Timing locked, won't follow the map | DFI module not in bypass mode |
| Wrong spark on the wrong cylinder | Ignition Mode not set to Distributor while running the DFI module |
| No RPM signal | Trigger pointed at the unused crank sensor, or trigger ground missing |
| MAP pegged under boost | Still on the factory 1-bar sensor |
| Temperature readings way off | Wrong calibration file, or pull-up disabled |
Wiring diagrams and FAQ
Factory ECU pinouts and wiring diagrams for the VN to VP, VR and VS to VX engines are handy when you're tracing a loom. Need these diagrams? Ask us and we'll send them over with advice for your build.
Can I keep the factory ECU and add a Haltech?
Yes, on VR onward the Elite 750 piggyback route keeps the OEM ECU for everything except fuel and ignition.
Do I have to remove the DFI module?
No. Most installs keep it and run the ECU in Distributor mode. Removing it is only worth doing if you want true direct fire control.
Working on other GM engines? See our pages on the Holden 5.0L V8, the Alloytec V6 and the LS1.
