Series 40E Troubleshooting – Section 16.1 Signal Functions – ATA Communications

The signal functions include the Data Communication Link and the ATA Diagnostic/Programming Link. See Figure
“ATA Communications Function Diagram”

.‪

Figure 1. ATA Communications Function Diagram

Data Communication Link — The signal is a 0 to 5 volt variable width square wave form signal that enables communication between the electronic service tool (EST) and the ECM. It is used for communication of diagnostic and calibration data. For data link wiring, see Figure
“Data Link”

.‪

Figure 2. Data Link

ATA Diagnostic/Programming Link — The ATA signal is a 0 to 5 volt width square wave form signal that enables communication between the ECM and the EST. It is used for communication of calibration, programming and diagnostic information.‪

Dash Board Information — Information on the ATA communication link is used to operate five different functions on the instrument cluster. They include:‪

• Oil Pressure
• Tachometer (Engine Speed)
• Speedometer
• Coolant Temperature
• Battery Voltage

Section 16.1.1
Fault Detection/Management

On a continuous basis, the ECM can detect an open, short or intermittent connection on the ATA lines. If an active fault occurs on the ATA lines, the instrument cluster and/or the EST will not display data. A typical 31–pin connector is shown below. Connection descriptions are listed in Table
“Recommended 31–pin Connector Pin Definitions”

.‪

To VIH 31-pin‪		Description‪	To ECM 60-pin‪	To VIH 31-pin‪		Description‪	To ECM 60-pin‪
1‪	A‪	Ignition Run Power‪	-‪	19‪	V‪	Vehicle Speed Control Throttle Device Ref‪	3‪
2‪	B‪	Data Link (+)‪	16‪	20‪	W‪	Engine Speed Control Throttle Device Ground‪	6‪
3‪	C‪	Data Link (-)‪	17‪	21‪	X‪	Variable Engine Speed Control Throttle Signal‪	30‪
4‪	D‪	Diagnostic Request‪	34‪	22‪	Z‪	Engine Speed Control Throttle Device Ref‪	5‪
5‪	E‪	Stop Engine Light (SEL) and Alarm‪	54‪	23‪	a‪	Required Stationary Signal No. 2 or Driveline Status‪	26‪
6‪	F‪	Check Engine Light (CEL)‪	55‪	24‪	b‪	Crank Inhibit Signal‪	46‪
7‪	G‪	Service Interval Lamp‪	45‪	25‪	c‪	Ignition Crank Power to Crank Inhibit Relay‪	-‪
8‪	H‪	Tachometer‪	59‪	26‪	d‪	Vehicle Speed No. 1 (+)‪	39‪
9‪	J‪	Cruise ON/OFF‪	35‪	27‪	e‪	Vehicle Speed No. 2 (-)‪	40‪
10‪	K‪	Cruise Resume/Accel, PTO Preset No. 2 or Fast Idle No. 2‪	31‪	28‪	f‪	OEM Discretionary for 31-pin Design‪	-‪
11‪	L‪	Cruise Set/Coast, PTO Preset No. 1, or Fast Idle No. 1‪	32‪	29‪	g‪	OEM Discretionary for 31-pin Design‪	-‪
12‪	M‪	PTO ON/OFF‪	36‪	30‪	h‪	Vehicle Retarder Output‪	47‪
13‪	N‪	PTO Preset ON/OFF or Fast Idle ON/OFF‪	37‪	31‪	j‪	Vehicle Retarder ON/OFF‪	‪
14‪	P‪	Required Stationary Signal No. 1 or Brake Status No. 1‪	43‪	‪
15‪	R‪	Required Stationary Signal No. 3 or Brake Status No. 2‪	44‪
16‪	S‪	Idle Validation‪	27‪
17‪	T‪	Vehicle Speed Control Throttle Device Ground‪	11‪
18‪	U‪	Variable Speed Control Throttle Signal or .25 V Engine Speed Control Signal‪	8‪

Key ON, Engine Off voltage checks at the EST connector are listed in Table
“Voltage Checks at EST Connector”

. Check with the breakout box installed and the ignition key ON, engine OFF. ‪

+ Test Points‪	Spec.‪	Signal‪	Comments‪
C to E‪	B+‪	Power‪	Should be power at C at all times. If no power, check ground and power circuits‪

EST connector checks to ground are listed in Table
“EST Checks to Ground”

. Check with the positive battery cable disconnected and the ignition key OFF. (If applicable, check with the dash connector unplugged.)‪

Test Points‪	Spec.‪	Signal‪	Comments‪
EST‪
A to Grd.‪	>1,000 Ω‪	ATA +‪	Less than 1,000 Ω indicates a short to ground either thru the harness or internal in the ECM. Disconnect the ECM and measure to ground again. If the short is still present, repair the harness.‪
B to Grd.‪	>1,000 Ω‪	ATA -‪
C to Grd.‪	>1,000 Ω‪	PWR‪	With Fuse F11 removed, a reading less than 1,000 Ω indicates a short to ground.‪
E to Grd.‪	<5 Ω‪	GRD‪	More than 5 Ω indicates an open circuit and will cause the EST tool not to power up.‪

EST resistance checks are listed in Table
“Electronic Service Tool Resistance Checks”

. Check with the breakout box installed and the ignition key OFF. ‪

Test Points‪	Spec.‪	Signal‪	Comments‪
EST Connector‪
A to No. 16‪	<5 Ω‪	ATA+‪	Resistance from ECM chassis connector (black) to EST connector‪
B to No. 17‪	<5 Ω‪	ATA-‪	Resistance from ECM chassis connector (black) to EST connector‪
C‪	<5 Ω‪	PWR‪	Resistance from EST connector to power fuse‪
E to Grd.‪	<5 Ω‪	GRD‪	More than 5 Ω indicates an open circuit and will cause the EST tool not to power up.‪

Fault Code Descriptions: 231 = ATA Common Fault — ATA wiring or connector faults, interference on data bus (e.g. dash or WTEC controller), faulty ECM.‪

• No data stream or Fault Codes displayed on EST or EST will not power up.
• If applicable, the dash display for speedometer, tachometer, oil pressure, coolant temperature and battery voltage does not function.

Section 16.1.2
ATA Communication

The ATA circuit uses a twisted wire pair. All repairs to this pair must maintain one complete twist per inch along the entire length of the circuit. This circuit is polarized (one positive and one negative) and reversing the polarity of this circuit will disrupt communications.‪

The ATA data link is defined by SAE recommended practices J1708 and J1587. This link and connector were adopted by the Recommended Practices 1201 and 1202.‪

All communications between the EST and the engine control system pass through the EST connector. See Figure
“ATA Communication”

. This communication link supports:‪

• Displaying fault codes and operating conditions on the EST
• Performing proprietary diagnostic tests programmed into the cartridge
• Clearing fault codes
• Programming performance parameter values
• Programming calibrations and strategies

The EST connector 384, has six pins labeled A through F. Fused battery power is provided to Pin C to provide battery power for electronic service tools. Pin E provides a battery ground for the EST. ‪

Figure 3. ATA Communication

Section 16.1.3
EST Connector 384

The engine control system does not detect faults in the power or ground circuits to EST connector 384. If the service tool does not power up when connected, try the service tool on another vehicle if one is available to determine if the service tool is working properly. If the service tool is okay, then check the power and ground circuits at the ATA connection.‪

Section 16.1.4
EST Displays

Should the EST display NO DATA, the ATA data link circuit from the EST connector to the ECM may be disrupted. Verify that the key is ON and then perform diagnostic steps. ‪

Section 16.1.5
Fault Code

Flash Code 231‪

ATA Code SID 250 FMI 2‪

ECM: ATA COMMON FAULT‪

Section 16.1.5.1
Symptom

Code 231 does not turn the Engine Warning light ON. This code can occur when the ECM cannot access the ATA data link. If this occurs, there will not be any ATA data available with the EST. The fault code may be flashed using the STI switch located on the instrument panel.‪

Section 16.1.5.2
Wiring Causes

ATA positive or negative circuits between EST and ECM and any other electronic devices (transmissions, brakes, etc.) using the ATA bus: Shorted (high or low), open, or busy (too many devices).‪

Note: On vehicles equipped with the WTEC transmission, this code may be present when attempting to program the ECM. The WTEC controller must be disconnected when programming the engine ECM.

Section 16.1.5.3
System Causes

System causes can include:‪

1. A defective ATA device (e.g. transmission controller or antilock brake controller) connected to the ATA bus is pulling the signal to ground.
2. Too many ATA devices, although this would be rare.
3. If no system causes are present, replace the ECM with a known good ECM.

Section 16.1.6
Instrument Cluster Display

The instrument cluster utilizes data on the ATA lines for the display of:‪

• Oil pressure
• Tachometer (engine speed)
• Speedometer
• Coolant temperature
• Battery voltage

The data is transmitted on the same ATA link that supplies information to the EST and the WTEC transmission controller. A microprocessor in the instrument cluster converts the ATA data into signals that will drive the various gages in the dash. ‪