PINPOINT TEST DX: Engine Coolant Temperature (ECT) Sensor: Introduction

WARNING: This page does not describe the selected car, but rather 25 other vehicles, including the 2012 Lincoln Navigator L, 2012 Lincoln Navigator, 2012 Lincoln MKZ, 2012 Lincoln MKX, and 2012 Lincoln MKT. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Engine coolant temperature must be greater than 10°C (50°F) to pass the KOEO self-test and greater than 82°C (180°F) to pass the KOER self-test. To accomplish this, the engine must be at normal operating temperature.

This pinpoint test is intended to diagnose the following:

ECT sensor (12A648)
harness circuits: ECT and SIGRTN
powertrain control module (PCM) (12A650)

Voltage values calculated for VREF equals 5 volts. These values may vary by 15% due to sensor and VREF variations.

Fig 1: Engine Coolant Temperature (ECT) Sensor Voltage Graph

Courtesy of FORD MOTOR CO.

TEMPERATURE SENSOR VOLTAGE AND RESISTANCE SPECIFICATIONS

Temperature		Temperature Sensor Values
°C	°F	Voltage	Resistance (K ohms)
120	248	0.28	1.18
110	230	0.36	1.55
100	212	0.47	2.07
90	194	0.61	2.80
80	176	0.80	3.84
70	158	1.05	5.37
60	140	1.37	7.70
50	122	1.77	10.97
40	104	2.23	16.15
30	86	2.74	24.27
20	68	3.26	37.30
10	50	3.73	58.75
0	32	4.14	95.85
-10	14	4.45	160.31

Fig 2: Identifying Engine Coolant Temperature (ECT) Sensor Connector

Courtesy of FORD MOTOR CO.

Powertrain Control Module (PCM) Connector

For PCM connector views or reference values, refer to REFERENCE VALUES article.

Vehicle	Connector	Pin	Circuit
Fiesta	128 PIN	E3	SIGRTN
Fiesta	128 PIN	E15	ECT
Focus	154 PIN	E33	SIGRTN
Focus	154 PIN	E12	ECT
Mustang	190-PIN	E32	SIGRTN
Mustang	190-PIN	E31	ECT
All other vehicles	154 PIN	E34	SIGRTN
All other vehicles	154 PIN	E12	ECT