The 1987 TBI Logic Module

[ Natural Connector | Black Connector ]


This page contains information specific to the 1987 TBI (throttle body injected, non-turbo) logic modules.  If you are not familiar with what the logic module is, please see the Understanding The Chrysler Engine Control Unit page before reading this one.

These logic modules use a Motorola 6803 processor.  The software and calibration tables are stored in a single 16kx8 EPROM (27C128) and a new 6840 timer chip was added to improve the accuracy of things like ignition and injector firings and reduce the loop time of the software to 22 miiliseconds.  The MAP sensor was moved to the engine bay on the passenger side strut tower to cure the problem of freezing water collecting in the sensor.  Also, the canister purge and EGR solenoids were merged into a single solenoid and the speed control electronics (if equipped with cruise control) were moved from the speed control servo to the logic module.  There were also a few other pin-out changes.

The 1987 TBI logic modules were not used in L-body vehicles because the TBI engine was not available for it.  The L-bodies had either the carbureted or turbocharged 2.2L engine.


The logic module has two 25-pin connectors.  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

Natural connector

Pin Circuit Wire Gauge Wire Color Function
1 K8 20 VT/WT* 5.0V power supply to MAP sensor
2 K16 22 VT/YL* Injector control signal
3 - - - Not used
4 K3 22 BK/PK* Power loss/check engine lamp output
5 R31 22 DG/OR* Voltage regulation signal
6 K15 22 YL Anti dwell signal
7 K14 18 DB/WT* Ignition "start"/"run" feed from power module (J2)
8 K14 18 DB/WT* Ignition "start"/"run" feed from power module (J2)
9 G7 22 WT/OR* Speed/distance sensor signal
10 N7 18 GY/BK* Ignition reference sensor signal
11 DK21 20 PK Serial communications interface (TX)
12 T21 22 GY/LB* Tachometer gauge signal
13 DK20 20 LG Serial communications interface (RX)
14 Z6 22 LB/BK* Navigator fuel monitor signal
15 U3 20 OR/BK* Fuel pacer lamp
16 N4 18 BK/YL* AIS motor output (winding 2)
17 K19 20 DB/YL* ASD relay output to power module
18 N1 18 GY/RD* AIS motor output (winding 2)
19 - - - Not used
20 N3 18 VT/BK* AIS motor output (winding 1)
21 C27 20 DB/PK* Radiator fan relay output
22 N2 18 BR/WT* AIS motor output (winding 1)
23 N6 18 OR 7.5V power supply from power module
24 K5 18 BK/WT* Signal ground source from top rear of engine
25 N5 18 BK/LB* Signal ground to sensors

Black Connector

Pin Circuit Wire Gauge Wire Color Function
1 K6 18 OR/WT* 5.0V power supply to TPS
2 J11 20 RD/WT* Direct battery feed (via power module)
3 N13 20 DB/OR* A/C cutout relay output
4 X36 20 TN/RD* Speed control solenoid vacuum output
5 S6 20 GY/YL* Canister purge and EGR solenoid output
6 X35 20 LG/RD* Speed control solenoid vent output
7 K9 18 LB/RD* Power ground source from top rear of engine
8 K9 18 LB/RD* Power ground source from top rear of engine
9 X31 22 BR/RD* Speed control switch set signal
10 X33 22 WT Speed control switch resume signal
11 C2 18 BR A/C damped pressure switch signal
12 S4 20 BR/YL* Park/neutral safety switch signal
13 D40 18 WT/PK* Brake switch signal
14 - - - Not used
15 X32 22 YL/RD* Speed control switch on/off signal
16 - - - Not used
17 - - - Not used
18 N11 18 BK Oxygen sensor signal
19 K4 20 DG/RD* MAP sensor signal
20 K22 22 RD/BK* Battery temperature sensor signal
21 K7 18 OR/DB* Throttle position sensor (TPS) signal
22 J11 20 RD/WT* Voltage regulation sense signal
23 K10 20 TN/BK* Coolant temperature sensor signal
24 - - - Not used
25 K13 18 BK/RD* Throttle body temperature sensor signal

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Updated 12/08/2004.

Copyright © 1996-2004 Russ W. Knize.