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This page contains the ecm connector identification and the terminal pin id's.
Below is the pinouts for the ecm #'s 1226870 (1985 only) and 1227165 (1986-89) Make note that the 1985 ecm/harness is NOT interchangeable with the 1986-89 ecm/harness.
NOTE: The charts below need to be used with a digital voltmeter to help save time in troubleshooting. Voltages listed may be different due to battery condition and alternator charging rates.
The following must be met to insure accurate readings: (A) Engine at operating temperature (B) Engine in "closed loop" operation (C) ALDL pins "A" and "B" not jumpered (diagnostic test mode) or Scanner connector not plugged into ALDL terminal.
Bookmarks:
1986-89 pinouts (ecm #1227165)
1990-92 speed density f-body (ecm#1227730)
1990-91 speed density (Corvette ecm #1227727)
| Circuit | Pin | Wire Color* | V. "Key On" | V. "Eng. On" |
| Fuel Pump Relay | A1 | Dk Grn/Wht | 0 | 13.9 |
| Air Switch | A2 | Brn | 12 | 13.9 |
| Canister purge | A3 | Dk Grn/Yel | 12 | 0 |
| EGR control | A4 | Gray | 12 | 0 |
| SES control | A5 | Brn/Wht | 0 | 13.9 |
| IGN-ECM | A6 | Pnk/Blk | 12 | 13.9 |
| TCC control | A7 | Tan/Blk | 12 | 13.9 |
| Serial data | A8 | Org | 2-5 | 2-5 |
| Diagnostic term | A9 | Wht/Blk | 5 | 5 |
| Speed sensor | A10 | Brn | (a) | (a) |
| MAT | A11 | Tan | (b) | (b) |
| Grd. | A12 | Blk/Wht | 0 | 0 |
| Battery 12V | B1 | Org | 12 | 13.9 |
| Fuel pump sig. | B2 | Red | 0 (c) | 13.9 |
| EST ref. low | B3 | Blk/Rd | 0 | 0 |
| EST control | B4 | Wht | 0 | 1.3 |
| EST ref. in | B5 | Ppl/Wht | 0 | 1.3 |
| Not Used | B6 | -------------- | --------------- | --------------- |
| EST signal | B7 | Blk | 9.2 | 9.3 |
| A/C signal | B8 | Grn/Wht | 0 | 0 |
| Not Used | B9 | --------------- | ---------------- | --------------- |
| P/N sw. signal | B10 | Org/Blk | 12 | 13.9 |
| MAF signal | B11 | Dk. Grn | 0 | .5-1.0 |
| Not Used | B12 | --------------- | --------------- | --------------- |
| Not Used | C1 | --------------- | --------------- | --------------- |
| Air Control | C2 | Blk/Pnk | 12 | 0 |
| IAC "B" low | C3 | Lt. Grn/Blk | not useable | not useable |
| IAC "B" high | C4 | Lt. Grn/Wht | " " | " " |
| IAC "A" high | C5 | Lt. Blu/Wht | " " | " " |
| IAC "A" low | C6 | Lt. Blu/Blk | " " | " " |
| Overdrive req. | C7 | Blk/Blu | 0 | 0 |
| A/T 4th gear or M/T 1st gear | C8 | Blu | 0 | 0 |
| Fan request | C9 | Dk. Grn | -- | -- |
| CST signal | C10 | Yel | 1.6 (d) | 1.6 (d) |
| Not Used | C11 | --------------- | --------------- | --------------- |
| TPS back up mode signal | C12 | Dk. Blu | .54V +/-.05V | .54V +/-.05V |
| TPS signal | C13 | Dk. Blu | .54V +/-.05V | .54V +/-.05V |
| TPS 5V ref | C14 | Gry | 5 | 5 |
| Inj.2-4-6-8 "B" | C15 | Lt. Grn | 12 | 13.9 |
| Battery 12V | C16 | Org | 12 | 13.9 |
| Grd | D1 | Blk/Wht | 0 | 0 |
| Cooling fan cntrl | D2 | Grn/Wht | 12 | 13.9 |
| Cyl. sel. (8 cyl. grd'd) | D3 | Blk/Wht | 0 | 0 |
| Not Used | D4 | --------------- | --------------- | --------------- |
| EST bypass | D5 | Tan/Blk | 0 | 4.6 |
| Grn'd O2 | D6 | Tan | 0 | 0 |
| O2 sensor sig. | D7 | Ppl | (e) | (e) |
| EGR temp. sw. | D8 | Grn | 12 | 13.9 |
| Not Used | D9 | --------------- | --------------- | --------------- |
| MAF grd. | D10 | Blk/Wht | 0 | 0 |
| Not Used | D11 | --------------- | --------------- | --------------- |
| TPS 5V grd | D12 | Blk | 0 | 0 |
| CST, MAF, MAT grd. | D13 | Blk | 0 | 0 |
| Inj.2-4-6-8 "B" | D14 | Lt. Grn | 12 | 13.9 |
| Inj.1-3-5-7 "A" | D15 | Lt. Blu | 12 | 13.9 |
| Inj.1-3-5-7 "A" | D16 | Lt. Blu | 12 | 13.9 |
Notes: (a) voltage varies from .60V to battery voltage depending on position of drive wheels. (b) varies with temperature (c) 12V first 2 seconds with ign. switch in "on" position (d) At normal operating temperature (e) varies, average of 0.45V.
1986-89 pinouts (ecm #1227165)
| Circuit | Pin | Wire Color* | V. Key "on" | V. Engine run |
| Fuel pump rly | A1 | Grn/wht | 0 (a) | 13.9 |
| Port air switch | A2 | Brn | 12 | 13.9 |
| Canister purge | A3 | Grn/Yel | 12 | 0 |
| EGR control | A4 | Gry | 12 | 0 |
| SES control | A5 | Brn/Wht | 0 | 13.9 |
| IGN, power | A6 | Pnk/blk | 12 | 13.9 |
| M/T od, or A/T TCC | A7 | Tan/Blk | 12 | 13.9 |
| Serial data | A8 | Org | 2-5V (varies) | 2-5V (varies) |
| Diagnostic term | A9 | Wht/Blk | 5 | 5 |
| Speed sensor | A10 | Brn | (b) | (b) |
| MAF analog grd return | A11 | Blk/Pnk | 0 | 0 |
| System ground | A12 | Blk/Wht | 0 | 0 |
| Battery 12V | B1 | Org | 12 | 13.9 |
| Fuel pump sig | B2 | Red | 0 | 13.9 |
| EST ref. low | B3 | Blk/Rd | 0 | 0 |
| Not Used | B4 | --------------- | --------------- | --------------- |
| Distributor ref. | B5 | Ppl/Wht | 0 | 1.5 |
| VATS signal | B6 | Wht | 2.5 | 2.5 |
| ESC signal | B7 | Blk | 9.2 | 9.3 |
| A/C signal | B8 | Grn/Yel | 0V off 12V on | 0V off 12V on |
| Not Used | B9 | --------------- | --------------- | --------------- |
| P/N switch | B10 | Org/Blk | 0V P/N 12V D | 0V P/N 12V D |
| Not Used | B11 | --------------- | --------------- | --------------- |
| MAF sensor in | B12 | Dk. Grn | 2.5 | .4-1.0 (c) |
| Fan rly cntrl | C1 | Dk. Grn/Wht | 12 | 13.9 |
| Converter air cntrl | C2 | Blk/Pnk | 12 | 0 |
| IAC "B" low | C3 | Lt. Grn/Blk | not useable | not useable |
| IAC "B" high | C4 | Lt. Grn/Wht | " " | " " |
| IAC "A" high | C5 | Lt. Blu/Wht | " " | " " |
| IAC "A" low | C6 | Lt. Blu/Blk | " " | " " |
| A/T OD switch | C7 | Blk/Blu | 12 | 13.9 |
| M/T OD req. | C8 | Blk/Blu | 0 | 0 |
| Not Used | C9 | --------------- | --------------- | --------------- |
| Coolant temp signal | C10 | Yel | 1.6(d) | 1.6 (d) |
| Not used | C11 | --------------- | --------------- | --------------- |
| MAT signal | C12 | Dk. Grn | (e) | (e) |
| TPS signal | C13 | Dk. Blu | .54V+-.05V | .54V+-.05V |
| TPS 5V ref | C14 | Gry | 5 | 5 |
| EGR temp sw. | C15 | Drk. Grn | 12 | 13.9 |
| Battery | C16 | Org | 12 | 13.9 |
| System grd | D1 | Blk/Wht | 0 | 0 |
| CTS, MAT, TPS 5V return | D2 | Blk | 0 | 0 |
| System grd | D3 | Blk/Wht | 0 | 0 |
| EST control | D4 | Wht | 0 | 1.3 |
| EST Bypass | D5 | Tan/Wht | 0 | 4.75 |
| Grn'd | D6 | Tan | 0 | 0 |
| O2 sensor sig. | D7 | Ppl | (f) | (f) |
| Not Used | D8 | --------------- | --------------- | --------------- |
| Not Used | D9 | --------------- | --------------- | --------------- |
| System Grd | D10 | Blk/Wht | 0 | 0 |
| A/C Press. Fan switch | D11 | Drk. Grn | 0 | 0 |
| MAF burn off relay | D12 | Blk | 12 | 13.9 |
| Not Used | D13 | --------------- | --------------- | --------------- |
| Not Used | D14 | --------------- | --------------- | --------------- |
| Inj.1-3-5-7 | D15 | Lt. Blu | 12 | 13.9 |
| Inj. 2-4-6-8 | D16 | Lt. Grn | 12 | 13.9 |
Notes: (a) 12V first 2 seconds with ign. in "on" position. (b) Varies between .60V and 12V depending on position of drive wheels. (c) varies with air flow into MAF sensor (d) At normal operating temperature. (e) varies with temperature (f) varies, averages 0.45V.
1990-92 speed density f-body (ecm#1227730) (Camaro/Firebird):
| Circuit | Pin | Wire Color* | V. Key "on" | V. Eng. "run" |
| MAP 5V ref. | A4 | Gry | 5 | 5 |
| TPS 5V ref. | A5 | Gry | 5 | 5 |
| Ign. Pwr feed | A6 | Pnk/Blk | 12 | 13.9 |
| Serial data | A8 | Org | 4.8 (a) | 4.8 (a) |
| Fuel pump rly | A11 | Dk. Grn/Wht | 0 (b) | 13.9 |
| ecm ground | A12 | Blk/Wht | 0 | 0 |
ecm pins A1,2,3,7,9,10 not used. Notes: (a) varies (b) 12V for 2 seconds with ign. key in "on" position.
| Circuit | Pin | Wire Color* | V. Key "on" | V. Eng. running |
| Battery | B1 | Org | 12 | 13.9 |
| TPS, MAT sensor ground | B5 | Blk | 0 | 0 |
| CTS, MAP sensor ground | B6 | Blk | 0 | 0 |
| VSS low | B9 | Ppl | (a) | (a) |
| VSS high | B10 | Yel | (a) | (a) |
| VSS to lp, 4K Pulse per mile (ppm) | B11 | Brn | 12 | 13.9 |
ecm pins not used: ,B2,3,4,7,8,12 Notes: (a) varies from .60V to 13.9V depending on position of drive wheels.
| Circuit | Pin | Wire color* | V. Key "on" | V. eng. running |
| Cruise control 2K ppm | C1 | Red | (a) | (a) |
| EST bypass | C7 | Tan/Blk | 0 | 5 |
| EST | C8 | Wht | 0 | 1.3 |
| A/C on request | C9 | Dk. Grn | 0-13.9V | 0-13.9V |
| Inj. 1-3-5-7 | C11 | Blk/Pnk | 12 | 13.9 |
| Inj. 2-4-6-8 | C12 | Blk/Grn | 12 | 13.9 |
| Battery 12V | C16 | Org | 12 | 13.9 |
ecm pins not used: C1,2,3,4,5,6,10,13,14,15 not used. notes: (a) varies from .60V to 13.9V depending on position of drive wheels.
| Circuit | Pin | Wire color* | V. key "on" | V. eng. running |
| ECM grd | D1 | Blk/wht | 0 | 0 |
| ecm ground | D6 | Blk/wht | 0 | 0 |
| ecm ground | D7 | Blk/wht | 0 | 0 |
| EST reference | D8 | Ppl/wht | 0 | 2.3 |
| EST ref. low | D9 | Blk/red | 0 | 0 |
| A/C press. fan switch, second fan | D12 | Gry | --- | --- |
| TCC 4th gear switch | D14 | Lt. Blu | 0 | 0 |
| P/N switch | D16 | Org/Blk | 0 | 0 |
ecm pins not used: D2,3,4,5,10,11,13,15.
| Circuit | Pin | Wire color* | V. Key "on" | V. Eng. running |
| IAC "A" high | E3 | Lt. Blu/wht | Not useable | Not useable |
| IAC "A" low | E4 | Lt. Blu/blk | " " | " " |
| IAC "B" high | E5 | Lt. Grn/wht | " " | " " |
| IAC "B" low | E6 | Lt. Grn/blk | " " | " " |
| SES light | E7 | Brn/wht | 0 | 13.9 |
| fan relay command input | E8 | Dk. Grn/wht | 0/12 | 0/13.9 |
| EGR sol. cntrl | E9 | Gray | 12 | 0 |
| Diagnostic term | E12 | Blk/wht | 2-5V | 2-5V |
| Fuel pump signal | E13 | Gray | 0 (a) | 13.9 |
| O2 signal | E14 | Ppl | (b) | (b) |
| O2 ground | E15 | Tan | 0 | 0 |
| CST signal | E16 | Yel | 1.6 (c) | 1.6 (c) |
ecm pins not used: E2,3,10,11. Notes: (a) 12V first 2 seconds with ign. key "on" (b) varies, average 0.45V (c) varies with temperature.
| Circuit | Pin | Wire color* | V. key "on" | V. eng. running |
| M/t shift lamp control | F1 | Tan/blk | 12 | 13.9 |
| Port sw. sol. | F2 | Brn | 0 | 0 |
| Diverter sol. | F4 | Blk/pnk | 0 | 0 |
| TCC cntrl A/T | F6 | Tan/blk | 12 | 13.9 |
| Canister purge | F7 | Dk. Grn/yel | 12 | 0 |
| ESC signal | F9 | Dk. Blu | ||
| VATS module | F10 | Dk. Blu | 2.5 | 2.5 |
| TPS signal | F13 | Dk. Blu | .54V +/-.075V | .54V +/-.075V |
| MAP signal | F15 | Lt Grn. | 1.6V (a) | 1.6V (a) |
| MAT signal | F16 | Tan | 1.6V (b) | 1.6V (b) |
ecm pins not used: F3,5,8,11,12,14. Notes: (a) varies with manifold pressure (b) varies with temperature.
1990-91 speed density (Corvette ecm #1227727)
Note: The last terminal #'s should be 22 not 21, read each row from left to right.
| Circuit | Pin ID | Wire Color* |
| IAC coil "A" HI | A1 | Drk. Blue/Wht |
| IAC coil "B" LO | A2 | Lt.. Grn/Blk |
| Secondary Cooling fan | A3 | Drk. Blue/Wht |
| EGR sol. Cntrl. | A4 | Gry |
| IAC coil "A" LO | A7 | Lt. Blue/Blk |
| IAC coil "B" HI | A8 | Lt. Grn/Wht |
| Primary Fan | A9 | Lt. Blue/Blk |
| Canister Purge | A10 | Drk Grn/Yel |
| Knock sensor | A11 | Drk. Blue |
| Upshift Light | A12 | Lt Grn/Blk/Tan-Blk |
| AC clutch cntrl | A13 | Red/Wht |
| O2 sensor input | A16 | Ppl. |
| PPM-CCM Radio | A17 | Drk. Grn/Wht |
| EAS Solenoid | A18 | Brn |
| EAC Solenoid | A19 | Blk/Pink |
| Fuel Pump signal | A20 | Red |
| O2 sensor ground | A22 | Tan |
ecm pins not used: A5,6, 14,15, 21. Connector A is yellow or grey or black.**
| Circuit | Pin ID | Wire Color* |
| Check engine lmp. | B1 | Brn/Wht |
| Diagnostic Term ALDL | B3 | Wht/Blk |
| Serial Data | B5 | Tan |
| VATS signal | B6 | Drk. Blue |
| AT TCC /MT 1-4 upshift | B7 | Tan/Blk or Drk Grn |
| PPM-CCM radio | B8 | Drk Grn/Wht |
| Ign. on power +12V | B10 | Pnk/Blk |
| Serial Data | B11 | Tan |
| AC request signal | B15 | Gry/Red |
ecm pins not used: B2,9, 12-14, 16-22. Connector B is red or white.**
| Circuit | Pin ID | Wire Color* |
| Battery Feed | C1 | Org. |
| VSS input | C2 | Yel. |
| Distr. Reference | C3 | Tan/Blk |
| MAT sensor signal | C4 | Tan |
| MAP/MAT grnd. | C5 | Blk/Pnk |
| ECM grnd | C6 | Blk/Wht |
| TPS 5V reference | C7 | Gry |
| VSS ground | C8 | Ppl |
| EST distributor | C9 | Wht |
| CTS,TPS, EOT grnd | C10 | Blk |
| MAP 5V reference | C12 | Gry |
| 1-4 upshift light | C13 | Yel/Blk |
| EOT sensor signal | C14 | Drk Grn/Org |
| TPS signal input | C15 | Drk Blue |
| CTS signal input | C16 | Yel |
| AC request signal | C17 | Drk. Blue |
| MAP signal input | C22 | Lt. Grn |
ecm pins not used: C11, 18-21. Connector C is green or grey.**
| Circuit | Pin ID | Wire Color* |
| Injectors 2,4,6,8 | D3 | Blk/Lt. Grn |
| Injector ground | D4 | Blk. |
| Fuel Pump relay driver | D7 | Drk. Grn/Wht |
| Injectors 1,3,5,7 | D9 | Blk/Pnk |
| Injector ground | D10 | Blk |
| Park/Neutral Sw. | D11 | Org/Blk |
| ECM ground | D12 | Blk/Wht |
| EST bypass | D13 | Ppl/Wht |
| BAT feed 12V | D17 | Org |
| EST reference grd | D19 | Blk/Red |
| Fan request signal | D21 | Drk Grn/Wht |
| AT 4th gear switch | D22 | Lt. Blue |
ecm pins not used: D1,2,5,6,14-16,18,20. Connector D is brown or blue.**
NOTES: (*) Wire colors may vary, always go by wire terminal identification. (**) Connector colors may vary, they will only fit into its specific slot.
Swapping pins on the early ecm connectors.
This will show you how to replace broken pins on the ecms except for the 1227727 ecm.
If you have access to a pin removal tool this will make it easier to swap the pins. This is a practiced art to depress the holding tab to remove the pin, so practice on a junk connector before you attempt to remove the pins on your harness.
The tool shown above is manufactured by Lisle. The part number is 14900. Retails for around $15.00. This tool is specially made to remove the terminals easily without damage. Also has a diagnostic ALDL test, small straight-slot screwdriver.
This
end is used for removing the terminals on the ecms
This rounded
end is perfect for removing the terminal pins on the TCC, TPS, old round style
VSS and many others. It will fit the male and female sides.
How to carefully remove the pins with out the Lisle tool.
1) Remove the terminal pin locking latch (A) from the back of the ecm connector. The terminal pin release slots are the outer slots. Do not use a removal tool in the inner slots, the terminal pin locking tab is not located here!
Note: Release
slots need to be on the left-hand side so release tool will be in proper
orientation.
After removing the locking latch, insert a very small 1/8" allen wrench or stiff wire (A) , while pushing slightly down and in until the tool contacts the terminal locking tab and releases. Tug on wire in back to see if it comes out, if not, repeat process until tab is released.
This picture
illustrates what is happening inside the connector.
After removal
and before installing into new or existing slot, bend the locking tab on the
terminal slightly upward so it will lock into place
After
installation, be sure to reinstall pin locking latch