NOTE: Regeneration may occur during normal operation. During regeneration, diagnostic procedures may display biased values. If a regeneration occurs during diagnostic procedures, allow the process to complete before continuing diagnostics.

This pinpoint test is intended to diagnose the following:

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

TEMPERATURE AND RESISTANCE VALUE SPECIFICATION (APPROXIMATE)

°C	°F	Ohms
100	212	2, 080
90	194	2, 803
80	176	3, 836
70	158	5, 337
60	140	7, 556
50	122	10, 908
45	113	13, 216
40	104	16, 092
35	95	19, 696
30	86	24, 329
25	77	30, 000
20	68	37, 352
15	59	46, 797
10	50	59, 016
5	41	74, 940
0	32	95, 851
-5	23	123, 485
-10	14	160, 313
-15	5	209, 816
-20	-4	276, 959
-30	-22	496, 051
-40	-40	925, 021

Fig 1: Engine Coolant Temperature (ECT) Sensor Connector

Courtesy of FORD MOTOR CO.

Vehicle	Connector	Pin	Circuit
F-650/F-750	A	2 1	SIGRTN ECT
All other vehicles	B	2 1	SIGRTN ECT

Fig 2: Powertrain Control Module-E (PCM-E) Connector

Courtesy of FORD MOTOR CO.

Vehicle	Connector	Pin	Circuit
Transit Connect	A	57	ECT
All other vehicles	B	36 34	SIGRTN ECT

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Pinpoint Tests K: Engine Coolant Temperature (ECT) Sensor: Introduction

Use the Manual With the Right Hardware

When to See a Mechanic

Rather have a pro handle this?