Applications GM LS1
Verified on the variant named in the note. Still set offset with a timing light on this car before enabling fuel.
GM LS1 / LS6 (Gen III)
F-body, C5, VT Commodore, Holden LS1. 24-tooth crank reluctor with an internally-conditioned sensor that the ECU must treat as Hall, plus a half-moon cam at the back of the block. Race Core F7 is the V8 sequential platform.
Recommended: Race Core F7 only. Eight sequential injectors, eight logic coils (LS truck / D585), cable-throttle stepper idle or a cable 90 mm without IAC, 24x decoder — not 36-1.
- Cylinders: 8
- Displacement: 5665 (LS1) · 5967 (LS6) cc
- Firing order: 1-8-7-2-6-5-4-3
- Orientation: Cylinder 1 front-left (driver side, conventional GM). Odd 1-3-5-7 left, even 2-4-6-8 right.
Variants
| Variant | Years | Trigger | Notes |
|---|---|---|---|
| LS1 5.7 | 1997–2004 | 24x crank (Hall-conditioned VR) + 1x half-moon cam | Black crank sensor. Cable throttle + stepper IAC on most. EV1 injectors ~24–28 lb/hr. |
| LS6 5.7 | 2001–2005 | 24x + half-moon cam | Higher compression, better head. Same decoder as LS1. |
| LM7 / 5.3 / 6.0 Gen III truck | 1999–2007 | 24x + cam | Same 24x. Often cable + stepper. Truck coils are the COP you want on everything. |
Recommended pin assignment (Race Core F7)
| Pin | TunerStudio | Function |
|---|---|---|
| B10 | Digital 1 | Crank 24x — treat as Hall (sensor is 3-wire) |
| B1 | Digital 2 | Cam half-moon Hall, rear of block |
| A3 | Lowside 1 | Injector cylinder 1 (EV1 / EV6 high-Z) |
| A15 | Lowside 2 | Injector cylinder 2 (EV1 / EV6 high-Z) |
| A4 | Lowside 3 | Injector cylinder 3 (EV1 / EV6 high-Z) |
| A16 | Lowside 4 | Injector cylinder 4 (EV1 / EV6 high-Z) |
| A5 | Lowside 5 | Injector cylinder 5 (EV1 / EV6 high-Z) |
| A6 | Lowside 6 | Injector cylinder 6 (EV1 / EV6 high-Z) |
| A7 | Lowside 7 | Injector cylinder 7 (EV1 / EV6 high-Z) |
| A19 | Lowside 8 | Injector cylinder 8 (EV1 / EV6 high-Z) |
| A35 | Ign 1 | Cyl 1 LS truck / D585 logic COP |
| A34 | Ign 2 | Cyl 2 LS truck / D585 logic COP |
| A22 | Ign 3 | Cyl 3 LS truck / D585 logic COP |
| A33 | Ign 4 | Cyl 4 LS truck / D585 logic COP |
| A32 | Ign 5 | Cyl 5 LS truck / D585 logic COP |
| A31 | Ign 6 | Cyl 6 LS truck / D585 logic COP |
| A30 | Ign 7 | Cyl 7 LS truck / D585 logic COP |
| A29 | Ign 8 | Cyl 8 LS truck / D585 logic COP |
| C20 | Analog Temp 3 | CLT |
| C30 | Analog Temp 2 | IAT |
| C13 | Analog Volt 1 | MAP 0–5 V |
| C24 | Analog Volt 2 | TPS 1 |
| C34 | Knock 1 | Knock bank 1 |
| C35 | Knock 2 | Knock bank 2 |
| A20 | Lowside 10 | Fuel-pump relay coil |
| A21 | Lowside 12 | Main-relay coil |
| A12 | Lowside 15 | Radiator-fan relay coil |
| B7/B6 + B15/B8 | ETB 1 ± / ETB 2 ± | Factory 4-wire stepper IAC (cable LS1) |
| B17 / B16 | CAN 1 H / L | Dash / wideband |
| B22 / B21 | CAN 2 H / L | Chassis / TCM |
| B18 | Battery Sense | Ignition-switched 12 V (5 A fuse) |
| B23 | +12 V MR | Main-relay 12 V into ECU |
| A17 A18 A24 B14 B19 B20 | Power GND | Engine block → battery − |
| C9 / C21 / C32 | 5 V Sens 1 | MAP, TPS 1, pedal 1 |
| C1–C8, C29, C31 | Sensor GND | All 0–5 V and thermistor returns |
Trigger
The 24x reluctor is unique. The sensor is a VR with internal signal conditioning, so the ECU sees a Hall-style square wave. TunerStudio: GM 24x (TT_GM_24x_5 / LS 24x) — never describe it as 36-1. Use the falling edge; the rising edge of a 24x is not evenly timed and will not decode. Gen III sensors are black; a grey Gen IV sensor on a 24x reluctor is the wrong part.
Crank
| Pattern | 24x. Named LS decoder. Not 36-1, not 60-2. |
| Sensor | 3-wire, above the starter, rear of the block. A: 12 V, B: signal ground, C: signal — confirm on the sensor you have; GM has swapped letters across years. Race Core: 12 V from C11/C23, signal Digital 1 (B10), ground sensor GND. |
| Edge | Falling. Rising is unique-timed and unusable. |
Cam
| Gen III | Half-moon Hall at the back of the valley. 3-wire. Digital 2 (B1). |
| Why | Sequential and COP need the cam. Wasted-spark first-start can skip it; do not skip it on an LS. |
TunerStudio
| Setting | Value |
|---|---|
| Wheel type | GM 24x / LS 24x |
| Invert primary | No. Pick falling edge. |
| Pull-up | On (Hall-style). |
| Firing order | 1-8-7-2-6-5-4-3 |
Offset: Lock 10°, light on cylinder 1 (left bank, front). 24x offset is usually a small number once the decoder is right — if you need 200°, you have the wrong edge.
- A cam swap that moves the half-moon edge across a 24x edge causes ‘trigger error’ after a cam install. Watch the composite log; a small cam offset recovers it.
- Gen IV 58x grey sensor and 58x reluctor are a different note (LS3).
Injection
High-Z EV1, ~3.5 Ω? No — LS1 injectors are high-Z ~12 Ω, 24–28 lb/hr (250–280 cc). Later 5.3 are similar. Sequential eight drivers. Returnless OEM — add a return on a swap.
| Impedance | High-Z ~12 Ω. Saturated. |
| OEM flow | LS1 ~24–28 lb/hr at 58 psi. Measure if they are 20 years old. |
| Mode | Sequential, cam sync. Wire by cylinder number, firing order in software. |
| Fuel | OEM returnless at ~400 kPa. A swap wants a return and a regulator referenced to MAP. |
Ignition
LS truck coils (D585) or LQ4 coils are 4-pin logic COP. 12 V, ground to the head, 5 V signal from Ign n, and sometimes a 5 V reference on pin D — follow the coil. Race Core Ign 1–8 in cylinder number order.
| Coils | Logic COP only. Never a dumb LS1 coil-near-plug without an igniter (early LS1 used an igniter in the module — most swaps already have truck coils). |
| Dwell | 2.5–3.0 ms running. They run hot if dwell is 5 ms or the ground is a body panel. |
| Wiring | Ign 1 (A35) → coil cyl 1, Ign 2 (A34) → cyl 2, … Firing order is software. |
Idle
Cable LS1 uses a 4-wire bipolar stepper in the throttle body. Same two H-bridges as every other stepper note. A 90 mm cable throttle without IAC idles on the blade plus a bypass screw — no stepper.
First start
- Load the matching variant configuration in TunerStudio before the harness is live — injectors and coils stay disconnected until the decoder is confirmed.
- Fuel pump fuse out. Coils unplugged or spark outputs disabled. Crank. Open Diagnostics → composite / high-speed logger.
- Confirm crank teeth are even, the missing-tooth (or named pattern) is a single clean gap, and cam is one pulse per two crank revolutions for sequential four-stroke.
- RPM during cranking should sit in the 150–350 rpm band. 0 rpm or 12,000 rpm means the decoder is lost — polarity or wheel type, not offset.
- Lock timing to a fixed 10° (idle control off). Timing light on cylinder 1. Change trigger offset until the damper agrees with 10°.
- Recheck at ~3,000 rpm. If timing walks with RPM, it is VR polarity, a delayed Hall, or the wrong decoder — not offset.
- Enable spark. Confirm a healthy burn (timing light or plug colour) with fuel still disabled.
- Enable fuel. Prime, then crank. Catch the first idle on a rich-safe VE, then lean toward stoich at idle.
- Only then enable closed-loop idle, VVT, boost and traction. A base map is a starting point, not a dyno tune.
A base map is a starting point, not a dyno tune.