Output Diagnostic Test Mode (DTM)
PurposeOutput Diagnostic Test Mode (DTM) is provided to check the mechanical motion and the electrical wiring of certain actuators.
Description
The actuators are checked acoustically or by touch. In some cases it might be necessary to use an LED tester for the fuel injectors, as the clicking sound from the injectors is very soft and short. Avoid background noise during audible check of the injectors.
When an audible "click" is heard from the actuator being tested, this only confirms that there is electrical current to the actuator and that the component is operating mechanically. The audible noise does not guarantee perfect component operation. Additional testing may be necessary.
This function can only be carried out with the engine OFF (not running) and the ignition switch turned ON. The ignition switch should remain ON throughout entire test. The DTM will be interrupted if the engine is started or if an engine speed pulse is detected.
The following components are activated by the Output DTM in the sequence given:
1 Fuel injector 1 (N 30)
2 Fuel injector 2 (N 31)
3 Fuel injector 3 (N 32)
4 Fuel injector 4 (N 33)
5 Fuel injector 5 (N 83)
6 Fuel injector 6 (N 84)
7 Idle Air Control (IAC) valve (N 71)
8 EVAP Canister Purge Regulator valve (N 80)
9 Heated Oxygen Sensor Relay (J 278)
10 EGR Vacuum Regulator Solenoid valve (N 18) *
11 Ignore display.Not applicable to this vehicle.
12 Secondary Air Injection pump relay (J 299) *
13 Secondary Air Injection solenoid valve (N 112) *
* Use Scan Tool display only if applicable to this vehicle.
EXAMPLE:
- Under normal circumstances the ECM will begin DTM component activation sequence with activation of Fuel Injector #1, followed by Injectors #2, #3, #4, etc. as shown in sequence list above.
- ECM will activate the Idle Air Control Valve after the Fuel Injectors.
- ECM will activate the EVAP Canister Purge Regulator valve after the Idle Air Control Valve.
- ECM will activate the Heated Oxygen Sensor Control Relay after the EVAP Canister Purge Regulator valve and so on. The component activation sequence NEVER changes.
OTHER POSSIBILITIES
- ECM DOES NOT automatically begin with the first component listed on the activation sequence (in this case first component is Fuel Injector for cylinder #1).
- It is possible to stop and exit the Output Diagnostic Test Mode mid-way through the component activation sequence.
- When this occurs the last component being activated will be stored in the ECM. THAT COMPONENT will be the first to be activated NEXT TIME the Output Diagnostic Test Mode is started.
NON-EXISTING COMPONENTS
- The EGR Vacuum Regulator Solenoid Valve is only installed on California emissions equipped vehicles, but will always be displayed/activated in sequence during DTM checking even if not installed on the vehicle.
- There is also a non-existing component with unknown component code that will be activated 11th in sequence during DTM checking. At present no component has been assigned to this sequence position. Just like the EGR frequency valve a component code display/activation will be given whether or not that component is actually installed on the vehicle
- Connect and start operation of VAG 1551, Refer to Connecting and Operating VAG 1551 Scan Tool
- Use function code 03. Display will appear as shown:
Output DTM
Injector - N 30
- To activate fuel injector for cylinder No. 1 (N 30) manually open and close the throttle valve.
Note: Fuel injector No. 1 must click, fuel injectors click very quietly.
If one or more injectors does NOT click, Check test procedures under individual component.
- To activate fuel injectors for cylinders 2 to 6, re-open and then close the throttle valve once for each injector.
Note: To select the next check or to skip an individual check, press -> button.
- To activate IAC (Idle Air Control) valve (N 71), press -> button, display will appear as shown:
Output DTM
Idle Air Control valve - N 71
The IAC valve must switch on and off until the next Output DTM is selected by pressing -> button.
If valve does not operate. Check test procedures under individual component.
- To activate EVAP Canister Purge Regulator valve (N 80), press -> button, display will appear as shown:
Output DTM
EVAP Canister Purge Regulator valve - N 8O
Note: The N8O valve must click until the next Output DTM is selected by pressing -> button.
If solenoid valve does NOT click, Check test procedures under individual component.
- While Output DTM is activated. Disconnect hose from N 80 valve (coming from carbon canister) attach auxiliary hose to N 80 valve, blow into hose. N 80 valve must open and close.
- To activate Heated Oxygen Sensor relay (J 278) press -> button, display will appear as shown:
Output DTM
Heated Oxygen Sensor relay - J 278
Note: The Heated Oxygen Sensor relay must click until the next Output DTM is selected by pressing -> button.
If relay does NOT click Check test procedures under individual component.
- To activate EGR Vacuum Regulator Solenoid valve (N 18) press -> button, display will appear as shown:
Output DTM
EGR vacuum Regulator Solenoid valve - N 18
Note: The N 18 valve must click until the next Output DTM is selected by pressing -> button.
If N 18 valve does NOT click, Check test procedures under individual component.
- Press -> button, display will appear,Ignore display.Not applicable to this vehicle. At present no component has been assigned to this sequence position.
- To activate Secondary Air Injection pump relay (J 299), press -> button, display will appear as shown:
Output DTM
Secondary Air Injection pump relay - J 299
Note: The J 299 relay must operate the Secondary Air Injection pump until the next Output DTM is selected by pressing -> button.
If Secondary Air Injection pump does NOT operate Check test procedures under individual component.
- To activate Secondary Air Injection solenoid valve (N 112), press -> button, display will appear as shown:
Output DTM
Secondary Air Injection solenoid valve - N 112
Note: The N 112 valve must click until the Output DTM is ended by pressing -> button.
If N 112 valve does NOT click, Check test procedures under individual component.