Geo/Suzuki Wiring

I’ve put together a brief summary of the wiring and sensors for the 1998-2001 Geo/Suzuki G13 engine. This 4 cylinder, 1.3L engine is rated between 75-79 HP at 5400 rpm, and is readily available in gently used Chevy/Geo Metros and Suzuki Swifts. It’s light weight and simplicity make it ideal for hovercraft, airboats, and experimental aircraft. It appears most people still prefer to convert pre OBD 2 engines (engines manufactured before Jan 1, 1996), but as these cars age and become more scarce, it is important to explore newer and more readily available options. Newer engines are typically more complicated, but offer greater performance due to innovations like multipoint fuel injection and variable valve timing. When searching for a donor car, I recommend finding a car with manual transmission, and no A/C or power steering. This will make the extraction simpler, but will not have a great effect on the necessary modifications to the wiring harness.

The wiring is fairly complicated, but much of the bulk is devoted to accessories that most builders won’t need (i.e. defrosters, wipers, interior lights, radio, etc.). Below I provide several tables and figures compiled from notes I made during my conversion.

The notes are broken into 4 sections:
1. Completed wiring harness – Picture of the completed wiring harness with all non-critical connections removed.
2. Connector tables – wire outs for the ECU/PCM connectors, with notes on which wires can be removed. In some cases where action such as rerouting of a wire is required to bypass systems (for example, bypassing the clutch pedal switch in the ignition system), there are a series of notes below with more details.
3. Wiring diagrams – detailed diagrams showing connections to the ECU/PCMN, engine sensors, and ignition/charging system. Non-critical wires that can be removed are highlighted.
4. Miscellaneous notes – Tips I’ve compiled to make the Geo/Suzuki extraction and conversion easier.

1. Completed Wiring Harness

Trimmed Geo/Suzuki wiring harness.

1.Fuel injectors
2.Intake air temperature sensor (IAT)
3.Oil level switch
4.Heated O2 sensor 1 (HO2S)
5.Ignition coil (timing belt side)
6.Ignition coil (flywheel side)
7.Camshaft position sensor (CMP)
8.Engine coolant temperature sensor (ECT)
9.Starter motor
10.Crankshaft position sensor (CKP)
11.Alternator
12.Manifold absolute pressure sensor (MAP)
13.Throttle position sensor (TPS)
14.Idle control valve
15.Datalink connector
16.Starter (hot)
17.Alternator (hot)
18.ECM/PCM
19.Heated O2 sensor 2 (HO2S) (optional)
20Fuse/relay box
21.Battery (+) terminal
22.Radiator fan
23.Ignition keyswitch and fuel pump

2. Connector Tables

The existing loom will have to be removed to trace wires through the harness. In an old car, the loom is likely brittle, and will need to be replaced anyway.
ECM Connector 1 (C21)

1.blk/grnCMP sensor gnd (top of engine)
2.wht/blupower/main fuse
3.pnk/bluEVAP canister air ventREMOVE
4.pnkOxygen sensor 2REMOVE
5.org/grnauto trans only (shift solenoid)REMOVE
6.orgauto trans only (shift solenoid)REMOVE
7.red/grnEVAP purge valveREMOVE
8.----
9.----
10.gry/redIgnition coil 1
11.brn/blkFuel injectors
12.brn/whtFuel injectors
13.blk/bluIdle speed control actuator
14.whtPower from junction fuse box
15.wht/bluPower to engine sensors
16.lt grn/redTank pressure control valveREMOVE
17.vio/yelCheck engine light (connect to an LED, and then to Fuse 21)
18.pnk/whtFuel pump relay
19.blu/blkMain power on
20.bluCooling fan systemREMOVE
21.----
22.----
23.gry/bluIgnition coil 2
24.brn/yelFuel injectors
25.brn/redFuel injectors
26.blk/redEngine sensor gnd

ECM Connector 2 (C22)

1.lt grnMAP and tank pressure sensors
2.orgCamshaft position sensor (CMP)
3.wht/blkCrank position sensor (CKP)
4.vio (or yel/grn)Vehicle speed sensor (VSS)REMOVE
5.org/grnManifold air pressure sensor (MAP)
6.lt grn/whtThrottle position sensor (TPS)
7.pnk/blkOxygen sensor 1 (HO2S)
8.---
9.lt grn/blkMany sensors (HO2S, MAP, ECT, IAT, TPS, etc.)
10.gry/wht
11.wht/redCrankshaft position sensor (CKP)
12.gry/yelVSS (auto trans only)REMOVE
13.redOxygen sensor 1 (HO2S)
14.gryIntake air temperature sensor (IAT)
15.blu/whtPower steering pressure switchREMOVE
16.blk/yelstarting, charging system and clutch pedal position switch (M/T only)See directions

ECM Connector 3 (C22)

1.----
2.red/yelIdle speed control actuator
3.grnA/T only
4.org/yelA/T only
5.org/blkA/T only
6.brnInstrument cluster/Tach signalSee notes
7.vio/grnDiagnosis monitor
8.blu/yelDiagnosis monitor
9.blk/bluInstrument clusterREMOVE
10.yelOxygen sensor 2 (HO2S)
11.yel/redFuel pump, level gauge, fuel meterSee notes
12.vio/whtDatalink connector
13.vio/redDiagnosis monitor and upshift indicatorSee notes
14.grn/bluA/T only
15.grn/redA/T only
16.redA/T only
17.grayAir conditioning REMOVE
18.brn/yelAccessoriesREMOVE
19.blu/redAir conditioning
20.blk/whtMany sensorsSee notes
21.lt grn/yelFuel tank pressure sensor REMOVE
22.lt grn/blkIAT, ECT, MAP, HO2S, TPS, etc.

3. Wiring Diagrams
The following wiring diagram gives pin outs for the three ECM connectors. All critical engine sensors are shown, and systems that can be removed are labeled ‘remove.’ Click on the picture for a larger version.

Though not a great help for modifying the wiring harness, I highly recommend purchasing the Haynes or Chilton manuals to help with removing the engine. As with any source, they are incomplete, but in my experience, the extra information is helpful.