A DTC symptom is a 2-digit number which adds additional detail to a DTC. The DTC symptom provides additional information without requiring a large increase in the number of new DTCs.
DTC Symptom Categories
The DTC symptom is made up of 2 alphanumeric digits. The first digit following the DTC indicates the DTC symptom category. There are 16 possible categories available in the range of 0 through the letter F. Currently there are 8 categories in use, 0 through 7. These 8 categories together with their definitions are given below.
Category Number | Category Name | Category Description |
|---|---|---|
0 | General Electrical Failures | This category includes standard wiring failure modes, direct current quantities related by Ohm's Law and quantities related to amplitude, frequency or rate of change, and wave shape. |
1 | Additional General Electrical Failures | This category includes the overflow from the previous category. |
2 | FM/PWM (Frequency/Pulse Width Modulated) Failures | This category includes faults related to frequency modulated and pulse width modulated inputs and outputs of the electronic control module (ECU). This category also includes faults where position is determined by counts. |
3 | ECU Internal Failures | This category includes faults related to memory, software, and internal electrical circuitry; requiring ECU replacement. |
4 | ECU Programming Failures | This category includes faults related to operational software, calibrations, and options, remedied by programming the ECU. |
5 | Algorithm Based Failures | This category includes faults based on comparing two or more input parameters for plausibility or comparing a single parameter to itself with respect to time. |
6 | Mechanical Failures | This category includes faults detected by inappropriate motion in response to an ECU controlled output. |
7 | Bus Signal/Message Failures | This category includes faults related to bus hardware and signal integrity. This category is also used when the physical input for a signal is located in one ECU and another ECU diagnoses the circuit. |
8-F | Reserved by Document | Not in use at this time. |
DTC Symptom Subtypes
The second digit of the DTC symptom is the subtype of the DTC symptom. These subtypes and their categories, together with their definitions, are given in the following table. DTC symptom 00 is a special case. If 00 is displayed, only the base code number and its description apply. Information regarding the fault will be provided in the code setting criteria.
Example
The DTC symptoms associated with each DTC provide more information about the fault that caused that DTC. An example of a DTC displayed can be B1451 05 where the B1451 is the DTC, and 05 after the space represents the DTC symptom. While the DTC indicates that the fault is in the accessory power circuit, this DTC symptom indicates the circuit is shorted to battery or open. Another possible symptom for this code is B1451 02, where B1451 indicates the accessory power circuit, and 02 indicates the circuit is shorted to ground.
DTC Symptom | DTC Symptom Description |
|---|---|
00 | No Additional Information |
01 | Short to Battery |
02 | Short to Ground |
03 | Voltage Below Threshold |
04 | Open Circuit |
05 | Short to Battery or Open |
06 | Short to Ground or Open |
07 | Voltage Above Threshold |
08 | Signal Invalid |
09 | Rate of Change Above Threshold |
0A | Rate of Change Below Threshold |
0B | Current Above Threshold |
0C | Current Below Threshold |
0D | Resistance Above Threshold |
0E | Resistance Below Threshold |
0F | Erratic |
10 | Reserved |
11 | Above Maximum Threshold |
12 | Below Minimum Threshold |
13 | Voltage Low/High Temperature |
14 | Voltage High/Low Temperature |
15 | Signal Rising Time Failure |
16 | Signal Falling Time Failure |
17 | Signal Shape/Waveform Failure |
18 | Signal Amplitude Less Than Minimum |
19 | Signal Amplitude Greater Than Maximum |
1A | Bias Level Out of Range |
1F | Intermittent |
21 | Incorrect Period |
22 | Low Time Less Than Minimum |
23 | Low Time Greater Than Maximum |
24 | High Time Less Than Minimum |
25 | High Time Greater Than Maximum |
26 | Frequency Too Low |
27 | Frequency Too High |
28 | Incorrect Frequency |
29 | Too Few Pulses |
2A | Too Many Pulses |
2B | Missing Reference |
2C | Reference Compare Error |
31 | General Checksum Failure |
32 | General Memory Failure |
33 | Special Memory Failure |
34 | RAM Failure |
35 | ROM Failure |
36 | EEPROM Failure |
37 | Watchdog/Safety Processor Failure |
38 | Supervision Software Failure |
39 | Internal Electronic Failure |
41 | Operational Software/Calibration Data Set Not Programmed |
42 | Calibration Data Set Not Programmed |
43 | EEPROM Error |
44 | Security Access Not Activated |
45 | Variant Not Programmed |
46 | Vehicle Configuration Not Programmed |
47 | VIN Not Programmed |
48 | Theft/Security Data Not Programmed |
49 | RAM Error |
4A | Checksum Error |
4B | Calibration Not Learned |
51 | Calculation Failure |
52 | Compare Failure |
53 | Temperature Low |
54 | Temperature High |
55 | Expected Number of Transitions/Events Not Reached |
56 | Allowable Number of Transitions/Events Exceeded |
57 | Expected Reaction After Event Did Not Occur |
58 | Incorrect Reaction After Event |
59 | Circuit/Component Protection Time-Out |
61 | Actuator Stuck |
62 | Actuator Stuck Open |
63 | Actuator Stuck Closed |
64 | Actuator Slipping |
65 | Emergency Position Not Reachable |
71 | Invalid Serial Data Received (Signal Validity Bit Indicates Failure) |
72 | Alive Counter Incorrect/Not Updated |
73 | Parity Error |
74 | Value of Signal Protection Calculation Incorrect |
75 | Signal Above Allowable Range |
76 | Signal Below Allowable Range |
7F | Erratic |
