For 1990-2009 cars

Table 1: | DTC Symptom

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 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 | DTC Symptom Descriptor
--- | ---
00 | No Additional Information
01 | Short to battery
02 | A 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 Failing 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 fault
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