Pinpoint Test DL: Cylinder Head Temperature (CHT) Sensor: Introduction

WARNING: This page is about a different variant/trim than selected.

WARNING: THIS VEHICLE IS EQUIPPED WITH HIGH VOLTAGE CABLES, COMPONENTS, AND WIRING. THE HIGH VOLTAGE WARNING LABELS CONTAINING THE HIGH VOLTAGE SYMBOL ARE LOCATED ON EACH HIGH VOLTAGE COMPONENT. HIGH VOLTAGE CABLES AND WIRING ARE ORANGE IN COLOR. CERTIFIED RUBBER INSULATING GLOVES AND A FACE SHIELD MUST BE WORN WHEN WORKING WITH THE HIGH VOLTAGE CABLES, COMPONENTS, OR WIRING. THE IGNITION KEY MUST BE CYCLED TO THE OFF POSITION FOR A MINIMUM OF 5 MINUTES, AND THE HIGH VOLTAGE TRACTION BATTERY SERVICE DISCONNECT PLUG PLACED IN THE SERVICING/SHIPPING POSITION BEFORE DISCONNECTING THE HIGH VOLTAGE CABLES. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY OR DEATH.
DO NOT DISCONNECT, DISABLE, OR TOUCH THE HIGH VOLTAGE CABLES, COMPONENTS, OR WIRING DURING THE MODULE REPROGRAMMING PROCEDURE BECAUSE HIGH VOLTAGE IS PRESENT. THE HIGH VOLTAGE WARNING LABELS CONTAINING THE HIGH VOLTAGE SYMBOL ARE LOCATED ON EACH HIGH VOLTAGE COMPONENT. HIGH VOLTAGE CABLES AND WIRING ARE ORANGE IN COLOR. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY OR DEATH.

This pinpoint test is intended to diagnose the following:

CHT sensor (6G004)
harness circuits: CHT, VREF, and SIGRTN
powertrain control module (PCM) (12A650)

On applications that do not use an engine coolant temperature (ECT) sensor, the CHT sensor is used to determine the engine coolant temperature in place of the ECT sensor. To cover the entire temperature range of both the CHT and ECT sensors, the PCM has a dual switching resistor circuit on the CHT input. A graph showing the temperature switching from the COLD END line to the HOT END line, with increasing temperature and back with decreasing temperature is included. Note the temperature to voltage overlap zone. Within this zone it is possible to have either a COLD END or HOT END voltage at the same temperature. For example, at 90°C (194°F) the voltage could read either 0.60 volt or 3.71 volts. Refer to the table for the temperature to voltage expected values.

Fig 1: Cylinder Head Temperature Sensor Voltage Graph

Courtesy of FORD MOTOR CO.

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

CYLINDER HEAD TEMPERATURE SENSOR EXPECTED VALUES

temperature		CHT Sensor Values
°C	°F	COLD END (volts)	HOT END (volts)	Resistance (K ohms)
-40	-40	4.89	-	965.808
-30	-22	4.81	-	513.019
-20	-4	4.67	-	283.664
-10	14	4.45	-	162.584
0	32	4.14	-	96.255
10	50	3.73	-	59.175
20	68	3.26	-	37.387
30	86	2.74	-	24.215
40	104	2.23	-	16.043
50	122	1.76	-	10.85
60	140	1.36	-	7.487
70	158	1.04	-	5.268
80	176	0.79	3.99	3.775
85	185	0.69	3.86	3.215
90	194	0.60	3.71	2.75
95	203	0.53	3.56	2.361
100	212	0.46	3.41	2.034
110	230	-	3.07	1.523
120	248	-	2.74	1.155
130	266	-	2.41	0.8866
140	284	-	2.10	0.6891
150	302	-	1.81	0.5417
160	320	-	1.55	0.4301
170	338	-	1.33	0.3449
180	356	-	1.13	0.2791
190	374	-	0.96	0.2278
200	392	-	0.82	0.1875
210	410	-	0.70	0.155
220	428	-	0.60	0.130
230	446	-	0.51	0.109
240	464	-	0.44	0.092
250	482		0.35	0.078
260	500		0.33	0.067

Fig 2: Cylinder Head Temperature (CHT) Sensor Connector

Courtesy of FORD MOTOR CO.

CYLINDER HEAD TEMPERATURE (CHT) SENSOR CONNECTOR PIN REFERENCE CHART

Pin	Circuit
2	SIGRTN (Signal Return)
1	CHT (Cylinder Head Temperature)

Fig 3: Powertrain Control Module (PCM) Connector

Courtesy of FORD MOTOR CO.

POWERTRAIN CONTROL MODULE (PCM) CONNECTOR PIN REFERENCE CHART

Pin	Circuit
E63	VREF (Reference Voltage)
E64	SIGRTN (Signal Return)
E15	CHT (Cylinder Head Temperature)