The 1987 TBI Logic Module

[ Natural Connector | Black Connector ]

Description

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.

Connectors

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.