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                                                                  ECM PINOUTS

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:

1985 pinouts (ecm #1226870) 

1986-89 pinouts (ecm #1227165)   

1990-92 speed density f-body (ecm#1227730)

1990-91 speed density (Corvette ecm #1227727)

                                                                                                   

1985 pinouts (ecm #1226870)      

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

 

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