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This page contains information specific to the 1988 and 1989 TBI (throttle body injected, non-turbo) Single Module Engine Controller (SMEC). If you are not familiar with what the SMEC is, please see the Understanding The Chrysler Engine Control Unit page before reading this one.
The SMEC uses a Motorola 6811 processor, which has twice the processing power of the 6803 that was used in the logic modules, reducing the loop time to 11 milliseconds. The software and calibration tables are stored in a single 16kx8 EEPROM (27C128).
Functionally, the 1988 and 1989 TBI SMECs are the same and are therefore interchangeable. Internally however they do differ, particularly in the software. The 1988 SMECs are based largely on the 1987 logic module code, while the 1989 SMECs appear to have a great deal of new code. This provided some additional functionality, such as greater on board diagnostic capability, returning from limp-in mode while driving if a sensor starts working again, etc).
The SMEC has two connectors: one bolt-on 60-way connector, which leads to the logic board and one 14-way large pin connector, which leads to the power board. The following sections contain a diagram and pin-out for each. The wire colors are in the color/tracer* format (BK/WT* = black wire with a white tracer). Below is a list of color abbreviations:
| Code | Color | Code | Color | Code | Color |
| BK | Black | LB | Light Blue | TN | Tan |
| BR | Brown | LG | Light Green | VT | Violet |
| DB | Dark Blue | OR | Orange | WT | White |
| DG | Dark Green | PK | Pink | YL | Yellow |
| GY | Grey | RD | Red | * | tracer |
| Pin | Circuit | Wire Gauge | Wire Color | Function |
| 1 | K4 | 20 | DG/RD* | MAP sensor signal |
| 2 | - | - | - | Not used |
| 3 | K10 | 20 | TN/WT* | Coolant temperature sensor signal |
| 4 | N5 | 18 | BK/LB* | Signal ground to sensors |
| 5 | K5 | 16 | BK/WT* | Signal ground source from top rear of engine |
| 6 | - | - | - | Not used |
| 7 | X33 | 20 | WT/LG* | Speed control switch resume signal |
| 8 | X32 | 20 | YL/RD* | Speed control switch on/off signal |
| 9 | X31 | 20 | BR/RD* | Speed control switch set signal |
| 10 | B1 | 18 | WT | Ignition "run" power feed |
| 11 | - | - | - | Not used |
| 12 | K14 | 18 | DB/WT* | Ignition "start"/"run" power feed from power board (J2) |
| 13 | K8 | 20 | VT/WT* | 5V power supply to MAP sensor and TPS |
| 14 | R31 | 20 | DG/OR* | Voltage regulation signal to power board |
| 15 | K9 | 18 | LB/RD* | Power ground source from top rear of engine |
| 16 | K9 | 18 | LB/RD* | Power ground source from top rear of engine |
| 17 | N2 | 18 | BR/WT* | AIS motor output (winding 1) |
| 18 | N4 | 18 | YL/BK* | AIS motor output (winding 2) |
| 19 | N1 | 18 | GY/RD* | AIS motor output (winding 2) |
| 20 | N3 | 18 | VT/BK* | AIS motor output (winding 1) |
| 21 | K13 | 18 | BK/RD* | Throttle body temperature sensor signal |
| 22 | K7 | 18 | OR/DB* | Throttle position sensor (TPS) signal |
| 23 | N11 | 18 | BK/DG* | Heated oxygen sensor signal |
| 24 | - | - | - | Not used |
| 25 | - | - | - | Not used |
| 26 | - | - | - | Not used |
| 27 | - | - | - | Not used |
| 28 | - | - | - | Not used |
| 29 | D40 | 18 | WT/PK* | Brake pedal switch signal |
| 30 | S4 | 20 | BR/YL* | Neutral safety switch signal |
| 31 | DK20 | 20 | LG | Serial communications interface (RX) |
| 32 | - | - | - | Not used |
| 33 | K16 | 20 | VT/YL* | Fuel injector control signal to power board |
| 34 | K15 | 20 | YL | Anti dwell control signal to power board |
| 35 | - | - | - | Not used |
| 36 | Z6 | 20 | LB/BK* | Fuel monitor signal to electronic navigator |
| 37 | - | - | - | Not used |
| 38 | - | - | - | Not used |
| 39 | - | - | - | Not used |
| 40 | S6 | 20 | GY/YL* | Exhaust gas return (EGR) solenoid output (California only) |
| 41 | J1 | 16 | RD | Direct battery feed |
| 42 | - | - | - | Not used |
| 43 | - | - | - | Not used |
| 44 | - | - | - | Not used |
| 45 | C20 | 18 | BR | A/C damped pressure switch signal |
| 46 | - | - | - | Not used |
| 47 | N7 | 18 | GY/BK* | Ignition reference sensor signal |
| 48 | G7 | 20 | WT/OR* | Speed/Distance sensor signal |
| 49 | - | - | - | Not used |
| 50 | T21 | 20 | GY/LB* | Tachometer signal to instrument cluster |
| 51 | DK21 | 20 | PK | Serial communications interface (TX) |
| 52 | N6 | 18 | OR | 8V power feed from power board |
| 53 | X36 | 20 | TN/RD* | Speed control servo output (vacuum) |
| 54 | K1 | 20 | PK/WT* | Purge canister solenoid output |
| 55 | U3 | 20 | OR/BK* | Shift indicator light output |
| 56 | N13 | 20 | DB/OR* | A/C cutout (WOT) relay output |
| 57 | C27 | 20 | DB/PK* | Radiator fan relay output |
| 58 | K19 | 20 | DB/YL* | ASD relay output |
| 59 | K3 | 20 | BK/PK* | Check engine lamp output |
| 60 | X35 | 20 | LG/RD* | Speed control servo output (vent) |
| Pin | Circuit | Wire Gauge | Wire Color | Function |
| 1 | N6 | 18 | OR | 8V power supply to logic board |
| 2 | K5 | 16 | BK/WT* | Signal ground source from top rear of engine |
| 3 | K14 | 18 | DB/WT* | Ignition "start"/"run" power feed to logic board and ASD relay (J2) |
| 4 | J2 | 14 | DB | Ignition "start"/"run" power feed |
| 5 | - | - | - | Not used |
| 6 | J9 | 16 | BK | Power ground source from top rear of engine |
| 7 | J9 | 16 | BK | Power ground source from top rear of engine |
| 8 | K16 | 20 | VT/YL* | Fuel injector control signal from logic board |
| 9 | Y11 | 18 | WT | Fuel injector driver output |
| 10 | - | - | - | Not used |
| 11 | R31 | 20 | DG/OR* | Voltage regulation signal from logic board |
| 12 | J5 | 18 | BK/YL* | Ignition coil driver output |
| 13 | K15 | 20 | YL | Anti dwell control signal from logic board |
| 14 | R3 | 18 | DG | Alternator field coil driver output |
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Return to the Engine Control Unit page |
Updated 12/08/2004.
Copyright © 1996-2004 Russ W. Knize.