LS3 Harness pin outs

Can anybody tell me (or crossout) the pins that need to be removed? 2009 LS3 harness

X1 pinout (73 way):
pin# wire color description
1 OG/BK Park/Neutral Switch (MYC)
2 -3 Not used
4 PU/WH - Starter Relay coil supply voltage
5-8 Not used
9 WH Brake pedal switch signal
10 PU/WH HO2S High Signal Bank 1 Sensor 2
11 TN/WH HO2S Low Signal Bank 1 Sensor 2
12 OG/BK A/C Refrigerant Pressure Sensor Signal
13 BK/WH Low Reference
14-15 Not used
16 D-BU Fuel Level Sensor Signal
17 Not Used
18 YE Accessory voltage
19 PK Ignition 1 Voltage
20 RD/WH Battery Positive Voltage
21-22 Not used
23 PU Low Reference
24 D-GN Fuel Tank Pressure Signal
25 Not used
26 D-BU Clutch pedal position sensor signal
27 TN Hi Speed GMLAM Serial Data Bus-
28 TN-BK Hi Speed GMLAM Serial Data Bus+
29 D-BU Accelerator pedal position (APP) Sensor 1 Signal
30 BN Low Reference
31 TN Low Reference
32 L-BU APP Sensor 2 Signal
33 GY 5 volt Reference 1
34 GY 5 volt Reference 1
35 Not used
36 TN 5 volt Reference 1
37 TN Intake air temperature (IAT) sensor signal
38 TN Low Reference
39-40 Not Used
41 YE MAF Sensor Signal
42 D-GN/WH Low reference
43-46 Not Used
47 PK Ignition 1 Voltage
48 WH Engine speed signal
49 TN HO2S Low Signal Bank 2 Sensor 2
50 D-GN/WH Fuel Pump Relay Control
51 Not used
52 PU/WH Starter Enable Relay Control
53 Not used
54 D-GN Clutch position sensor control
55 Not used
56 WH/BK 5 volt Reference 2 (5V2)
57 D-GN/WH VSS
58 D-GN Low Speed Cooling Fan relay Control
59 WH/BK Ignition 1 Relay control
60 Not used
61 WH EVAP Canister Vent Solenoid Control
62 Not used
63 D-GN/WH A/C Compressor Clutch Relay Control
64 OG/WH HO2S Heater Low Control Bank 2 Sensor 2
65 BN HO2S Heater Low Control Bank 1 Sensor 2
66 GY Skip/Shift Solenoid Control (M10)
67 Not used
68 BN/WH MIL Control Malfunction indicator Lamp control
69 PU HO2S High Signal Bank 2 Sensor 2
70 L-BU Fuel Level Sensor Signal-Secondary
71 YE VSS Signal High (M10)
72 PU VSS Signal Low (M10)
73 BK/WH Ground

X2 pinout (80 way):
pin# wire color description
1 Not used
2 L-GN 5 Volt Reference 2
3 L-BU/BK 5V2
4 Not used
5 BN TAC (throttle Actuator Control) Motor Control -2
6 YE TAC Motor Control -1
7 Not used
8 D-GN/WH EVAP Canister Purge Solenoid Control
9-10 Not used
11 L-GN Reverse Lockout Solenoid Control
12 GY/WH HO2S Heater Low Control Bank 1 Sensor 1
13 L-GN HO2S Heater Low Control Bank 2 Sensor 1
14-16 Not used
17 D-BU/WH Fuel Injector 8 Control
18 TN/WH Fuel Injector 5 Control
19 YE/BK Fuel Injector 6 Control
20 TN Fuel Injector 1 Control
21 YE Engine Coolant Temp Sensor Signal
22 TN Low Reference
23 TN/WH Transmission Fluid Temp Sensor Signal (M10)
24 OG/BK Low Refernce (M10)
25 Not used
26 D-BU Knock Sensor (KS) 1 Signal
27 GY Knock Sensor (KS) 1 Signal
28 Not used
29 L-BU Knock Sensor (KS) 2 Signal
30 GY Knock Sensor (KS) 2 Signal
31 Not used
32 GY Generator Field Duty Cycle Signal
33 BN Oil pressure Switch Signal
34 BK Low Reference
35 TN/WH Low Reference
36 Not used
37 L-GN/BK Fuel Injector 2 Control
38 PK/BK Fuel Injector 3 Control
39 L-BU/BK Fuel Injector 4 Control
40 OG/BK Fuel Injector 7 Control
41 GY 5 Volt Referencve 1
42 Not used
43 GY 5 Volt Referencve 1 LS3 or LS7
44 OG 5V1
45-49 Not used
50 TN/Wh Oil Pressure Sensor Signal
51-52 Not used
53 OG/BK Low Reference LS3 or LS7
54-55 Not used
56 TN HO2S Low Signal- Bank 1 Sensor 1
57 PU/WH HO2S High Signal- Bank 1 Sensor 1
58 L-GN MAP Sensor Signal
59 PU HO2S High Signal- Bank 2 Sensor 1
60 TN HO2S Low Signal- Bank 2 Sensor 1
61 OG Generator Turn On Signal
62 Not used
63 PU Throttle position sensor 2 signal
64 BN/WH Camshaft Position Signal (CMP)
65 D-GN TP Sensor 1 Signal
66 PK/BK Low Reference
67 Not used
68 D-BU/WH Crankshaft Position Sensor Signal
69 YE/BK Low Reference
70 PU IC 1 Control
71 PU/WH IC 8 Control
72 OG IC 7 Control
73 OG/WH IC 2 Control
74 L-BU/WH IC 6 Control
75 D-GN IC 5 Control
76 D-GN/WH IC 4 Control
77 L-BU IC 3 Control
78 BN Low Reference
79 BN/WH Low Reference
80 Not used

2009 LS3 Wiring Harness

X1 pinout (73 way):

pin# / wire / color / description
1 OG/BK Park/Neutral Switch (MYC) / To ground
2 -3 Not used
4 PU/WH - Starter Relay coil supply voltage
5-8 Not used
9 WH Brake pedal switch signal
10 PU/WH HO2S High Signal Bank 1 Sensor 2
11 TN/WH HO2S Low Signal Bank 1 Sensor 2
12 OG/BK A/C Refrigerant Pressure Sensor Signal
13 BK/WH Low Reference
14-15 Not used
16 D-BU Fuel Level Sensor Signal / Unsure, for emissions?
17 Not Used
18 YE Accessory voltage
19 PK Ignition 1 Voltage
20 RD/WH Battery Positive Voltage
21-22 Not used
23 PU Low Reference
24 D-GN Fuel Tank Pressure Signal / emissions?
25 Not used
26 D-BU Clutch pedal position sensor signal / Traction Control?
27 TN Hi Speed GMLAM Serial Data Bus- / to ALDL
28 TN-BK Hi Speed GMLAM Serial Data Bus+ / to ALDL
29 D-BU Accelerator pedal position (APP) Sensor 1 Signal / DBW Throttle Body
30 BN Low Reference
31 TN Low Reference
32 L-BU APP Sensor 2 Signal / DBW Throttle Body
33 GY 5 volt Reference 1
34 GY 5 volt Reference 1
35 Not used
36 TN 5 volt Reference 1
37 TN Intake air temperature (IAT) sensor signal
38 TN Low Reference
39-40 Not Used
41 YE MAF Sensor Signal / Mass AirFlow Sensor
42 D-GN/WH Low reference
43-46 Not Used
47 PK Ignition 1 Voltage
48 WH Engine speed signal / Tachometer
49 TN HO2S Low Signal Bank 2 Sensor 2 / Rear O2
50 D-GN/WH Fuel Pump Relay Control
51 Not used
52 PU/WH Starter Enable Relay Control
53 Not used
54 D-GN Clutch position sensor control
55 Not used
56 WH/BK 5 volt Reference 2 (5V2)
57 D-GN/WH VSS / To VSS Pickup
58 D-GN Low Speed Cooling Fan relay Control
59 WH/BK Ignition 1 Relay control
60 Not used
61 WH EVAP Canister Vent Solenoid Control / emissions
62 Not used
63 D-GN/WH A/C Compressor Clutch Relay Control
64 OG/WH HO2S Heater Low Control Bank 2 Sensor 2 / Rear O2
65 BN HO2S Heater Low Control Bank 1 Sensor 2 / Front O2
66 GY Skip/Shift Solenoid Control (M10) / auto trans...
67 Not used
68 BN/WH MIL Control Malfunction indicator Lamp control / Service Engine Light
69 PU HO2S High Signal Bank 2 Sensor 2 / Rear O2 / Rear O2
70 L-BU Fuel Level Sensor Signal-Secondary / emissions?
71 YE VSS Signal High (M10) / To VSS Pickup
72 PU VSS Signal Low (M10)
73 BK/WH Ground / Chassis ground

X2 pinout (80 way):

pin# / wire / color / description
1 Not used
2 L-GN 5 Volt Reference 2
3 L-BU/BK 5V2
4 Not used
5 BN TAC (throttle Actuator Control) Motor Control -2 / DBW
6 YE TAC Motor Control -1 / DBW
7 Not used
8 D-GN/WH EVAP Canister Purge Solenoid Control / emissions
9-10 Not used
11 L-GN Reverse Lockout Solenoid Control / auto trans OR T56
12 GY/WH HO2S Heater Low Control Bank 1 Sensor 1 / Front O2
13 L-GN HO2S Heater Low Control Bank 2 Sensor 1 / Rear O2
14-16 Not used
17 D-BU/WH Fuel Injector 8 Control
18 TN/WH Fuel Injector 5 Control
19 YE/BK Fuel Injector 6 Control
20 TN Fuel Injector 1 Control
21 YE Engine Coolant Temp Sensor Signal
22 TN Low Reference
23 TN/WH Transmission Fluid Temp Sensor Signal (M10) / auto trans...
24 OG/BK Low Reference (M10)
25 Not used
26 D-BU Knock Sensor (KS) 1 Signal
27 GY Knock Sensor (KS) 1 Signal
28 Not used
29 L-BU Knock Sensor (KS) 2 Signal
30 GY Knock Sensor (KS) 2 Signal
31 Not used
32 GY Generator Field Duty Cycle Signal
33 BN Oil pressure Switch Signal
34 BK Low Reference
35 TN/WH Low Reference
36 Not used
37 L-GN/BK Fuel Injector 2 Control
38 PK/BK Fuel Injector 3 Control
39 L-BU/BK Fuel Injector 4 Control
40 OG/BK Fuel Injector 7 Control
41 GY 5 Volt Reference 1
42 Not used
43 GY 5 Volt Reference 1 LS3 or LS7
44 OG 5V1
45-49 Not used
50 TN/Wh Oil Pressure Sensor Signal
51-52 Not used
53 OG/BK Low Reference LS3 or LS7
54-55 Not used
56 TN HO2S Low Signal- Bank 1 Sensor 1 / Front O2
57 PU/WH HO2S High Signal- Bank 1 Sensor 1 / Front O2
58 L-GN MAP Sensor Signal
59 PU HO2S High Signal- Bank 2 Sensor 1 / Rear O2
60 TN HO2S Low Signal- Bank 2 Sensor 1 / Rear O2
61 OG Generator Turn On Signal / Alternator
62 Not used
63 PU Throttle position sensor 2 signal
64 BN/WH Camshaft Position Signal (CMP)
65 D-GN TP Sensor 1 Signal
66 PK/BK Low Reference
67 Not used
68 D-BU/WH Crankshaft Position Sensor Signal
69 YE/BK Low Reference
70 PU IC 1 Control
71 PU/WH IC 8 Control
72 OG IC 7 Control
73 OG/WH IC 2 Control
74 L-BU/WH IC 6 Control
75 D-GN IC 5 Control
76 D-GN/WH IC 4 Control
77 L-BU IC 3 Control
78 BN Low Reference
79 BN/WH Low Reference
80 Not used

I'm not sure about #16 D-BU Fuel Level Sensor Signal & 24 D-GN Fuel Tank Pressure Signal, but everything else in BOLD can be removed. The 5V reference is needed for sensors, and (just as on the LT) 2 of the O2 sensors may be programmed out.

EAP / POC

Thanks Greg!

No Prob...

1 OG/BK Park/Neutral Switch (MYC) / To ground

Just making sure you got the notes @ the end...
Don't remove this just because it's BOLD...
It needs to remain, but be connected to ground.

OCD, maybe...but without a ground, She won't get crunk.

Okay. I took that wire out already but I didnt cut a single wire. I used tweezers to take out each pin not needed. So I can easily put that wire back in and ground it.

1 OG/BK Park/Neutral Switch (MYC) / To ground

Now you mean ground JUST that wire only and not ALL bold wires. Right? WHAT DOES MYC stand for? Multi year something?

Also, I believe I keep the front O2 sensors and remove the rears? You have it the other way around. Banks 1&2 sensor 1's are front and Banks 1&2 sensor 2's are rears? So, I removed the rears. Just based on the quick google search and logic in that the computer wants to see fuel ratio's straight away and not so much after a catalytic.

This is my first time doing this as my LT harness was done by RH via vendor.

BTW, if it works now, modding a harness is easy!

I found the wires for the drive by wire easily and the ALDL port. Im missing one wire for the ALDL port... "Pin 2 Class 2 Serial Data"

Theres only 6 wires that go to the ALDL port:
Pin 2 PU Class 2 Serial Data (missing)
Pin 4 BK Ground
Pin 5 BK/WH Ground
Pin 6 TN/BK High speed GMLAN Serial Data Bus + (straight off X1)
Pin 14 TN High speed GMLAN Serial Data Bus - (straight off X1 as well)
Pin 16 RD/WH Battery Positive Voltage

Very simple stuff.

I now need to order the ALDL connector GM PN# 12110250, the DBW connector GM PN# 15326830 and a fuse/relay center PN#????

944-LT1 wrote:Now you mean ground JUST that wire only and not ALL bold wires. Right?

Only that wire...Not sure what (MYC) is...
The neutral switch grounds the reference voltage when starting.

As far as easy...
"EAP / POC" = Easy as Pie / Piece of Cake
Time consuming, slightly...

Front O2s are correct...
(160+ lines in this text box gets crowded...)

Fuse / Relay Block:
AUTOZONE can order you the fuse block, with terminals for $5.00, part# is (Dorman) 85668.

OBD2 DIAGNOSTIC PORT WIRING
Pin 2 Missing? Even @ the PCM plug?

Fuse / Relay Block:
AUTOZONE can order you the fuse block, with terminals for $5.00, part# is (Dorman) 85668.

Awesome!

OBD2 DIAGNOSTIC PORT WIRING
Pin 2 Missing? Even @ the PCM plug?

I dont have a diagnostic port yet. I have 5 of 6 of the wires needed to hook one up from the ECM but am missing the wire that would go to pin 2 of the diagnostic port. Im guessing the missing wire comes from the BCM or someother computer in the car and gives diagnostics on things like suspension or whatever not related to the engine. Im thinking its not needed.

Okay....I guess pin 2 does a bit more than I thought.
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This is why I cant find that wire.

When the LS3 wiring mod is hammered out, I'll make it a Manual Revision.

Keep me posted...

I think it already is. Ive scoured over the schematics and sites for something to tell me im wrong but all looks legit.

but yeah, no good until it starts and runs.... Ill let you know!

944-LT1 wrote:I think it already is...

Awesome!
'Need to pinch that Fat Lady.