OBD2 Diagnostics reading project - Revision history

Mlines: /* Other modules found by a full scan */

2026-10-29T21:04:19Z

Other modules found by a full scan

Mlines: /* Other modules found by a full scan */

2026-10-29T20:31:59Z

Other modules found by a full scan

Mlines: /* Other modules found by a full scan */

2026-10-29T20:31:27Z

Other modules found by a full scan

Mlines: /* Other modules found by a full scan */

2026-10-29T20:21:08Z

Other modules found by a full scan

Mlines: /* Car Scanner Pro (working) */

2026-10-29T20:19:53Z

Car Scanner Pro (working)

Mlines: /* Car Scanner Pro (working) */

2026-10-29T20:18:01Z

Car Scanner Pro (working)

Mlines: /* Known problem */

2026-10-29T20:16:48Z

Known problem

Mlines: /* Torque Pro custom PIDs */

2026-10-29T20:16:09Z

Torque Pro custom PIDs

Mlines: /* Known problem */

2026-10-29T20:15:12Z

Known problem

Mlines: /* Calibration (provisional) */

2026-10-29T20:12:59Z

Calibration (provisional)

@@ Line 246: / Line 246: @@
 | 0x79A || 0x7AA || KWP || 37210-74PA, 37210-74PE* || Lighting and turn switch || Parts catalogue
 |-
-| 0x778 || 0x788 || KWP || 33990-52R0, 33990-78R8* || Dual sensor brake support (inferred) || By elimination
+| 0x778 || 0x788 || KWP || 33990-52R0, 33990-78R8* || Dual sensor brake support || Parts catalogue
 |-
 | 0x793 || 0x7A3 || UDS || 38910-77R0, 38910-78RC* || Airbag (SRS) controller || Parts catalogue

@@ Line 229: / Line 229: @@
 A full health-check scan with a Launch X431 CRP919, captured with PCAN-View on the OBD socket, shows 12 modules answering on the DLC. Every module that replied is listed here. The reply ID is not always the request ID plus 8.
 {| class="wikitable"
 ! Request !! Reply !! Protocol !! Identification replies !! Module !! How identified

@@ Line 256: / Line 256: @@
 | 0x751 || 0x761 || UDS || 33580-79R0, 33580-78R0* || none || Central gateway (matches label 33580-79R01)
 |}
+{| class="wikitable"
 Reply ID offsets: engine +0x08; 0x261 to 0x274 +0x400; all others +0x10.

@@ Line 262: / Line 262: @@
 * Requests to 0x273 and 0x262 (tester present) got no reply, so those modules are probably not fitted.
 * The "probable" and "possible" names are guesses from the part-number series and are not confirmed.
 == Open questions ==

← Older revision		Revision as of 20:19, 29 October 2026
Line 226:		Line 226:

	The start command has not yet been shortened. Adapter: Both dongle 1 (generic ELM327-based) and dongle 2 (Veepeak OBDCheck BLE+) work with Car Scanner Pro.		The start command has not yet been shortened. Adapter: Both dongle 1 (generic ELM327-based) and dongle 2 (Veepeak OBDCheck BLE+) work with Car Scanner Pro.
		+	== Other modules found by a full scan ==
		+	A full health-check scan with a Launch X431 CRP919, captured with PCAN-View on the OBD socket, shows 12 modules answering on the DLC. Every module that replied is listed here. The reply ID is not always the request ID plus 8.
		+
		+	{\| class="wikitable"
		+	! Request !! Reply !! Protocol !! Identification replies !! DTC reply !! Module
		+	\|-
		+	\| 0x7E0 \|\| 0x7E8 \|\| KWP \|\| 33980-78R0, 33980-78RC* \|\| none \|\| ECM
		+	\|-
		+	\| 0x261 \|\| 0x661 \|\| KWP \|\| 56100-77RA, 56100-78RF* \|\| none \|\| ABS (probable)
		+	\|-
		+	\| 0x263 \|\| 0x663 \|\| KWP \|\| 38720-77R0, 38720-77R0* \|\| none \|\| not yet identified
		+	\|-
		+	\| 0x271 \|\| 0x671 \|\| KWP \|\| 36775-77R0, 36775-77RC* \|\| none \|\| not yet identified
		+	\|-
		+	\| 0x274 \|\| 0x674 \|\| KWP \|\| 34100-78R0, 34110-78RD* \|\| none \|\| Instrument cluster (probable)
		+	\|-
		+	\| 0x798 \|\| 0x7A8 \|\| KWP \|\| 37160-61M0, 37120-78R0* \|\| 1 code (9A 31) \|\| TPMS controller
		+	\|-
		+	\| 0x79A \|\| 0x7AA \|\| KWP \|\| 37210-74PA, 37210-74PE* \|\| none \|\| not yet identified
		+	\|-
		+	\| 0x778 \|\| 0x788 \|\| KWP \|\| 33990-52R0, 33990-78R8* \|\| none \|\| not yet identified
		+	\|-
		+	\| 0x793 \|\| 0x7A3 \|\| UDS \|\| 38910-77R0, 38910-78RC* \|\| none \|\| SRS (probable)
		+	\|-
		+	\| 0x772 \|\| 0x782 \|\| UDS \|\| 38885-77R0, 38885-78R0* \|\| none \|\| EPS (possible)
		+	\|-
		+	\| 0x799 \|\| 0x7A9 \|\| UDS \|\| 38960-78RA, 38960-78RA* \|\| 1 record (92 4E 00, status 02) \|\| not yet identified
		+	\|-
		+	\| 0x751 \|\| 0x761 \|\| UDS \|\| 33580-79R0, 33580-78R0* \|\| none \|\| Central gateway (matches label 33580-79R01)
		+	\|}
		+
		+	Reply ID offsets: engine +0x08; 0x261 to 0x274 +0x400; all others +0x10.
		+
		+	* KWP-style modules answer <code>1A 8E</code> and <code>1A 8A</code> (identification) and <code>18 00 FF 00</code> (DTCs). UDS-style modules answer <code>22 F1 01</code> and <code>22 F1 88</code> (identification) and <code>19 02 FF</code> (DTCs).
		+	* Requests to 0x273 and 0x262 (tester present) got no reply, so those modules are probably not fitted.
		+	* The "probable" and "possible" names are guesses from the part-number series and are not confirmed.

	== Open questions ==		== Open questions ==

@@ Line 225: / Line 225: @@
 * Equations use the same letters as the table above, for example <code>Q*0.01372</code> for front left (bar)
-The start command has not yet been shortened. Adapter: [dongle 1 or 2, to be confirmed].
+The start command has not yet been shortened. Adapter: Both dongle 1 (generic ELM327-based) and dongle 2 (Veepeak OBDCheck BLE+) work with Car Scanner Pro.
 == Open questions ==

@@ Line 216: / Line 216: @@
 === Known problem ===
 Using dongle 1 (generic Chinese ELM327-based) with Torque Pro on the XTRONS PX90, Torque read bytes <code>A</code> to <code>D</code> (first line of the reply) correctly, but every byte from <code>E</code> onward returned -1, even though a terminal received the full 102 bytes with the same commands. The start-command field is applied (adding <code>ATH1</code> changed the output). Tried without success: turning off "Faster communication", removing <code>ATS0</code>. Not yet tried: <code>ATAT0, ATSTFF</code> timeout settings, other apps, and the Veepeak OBDCheck BLE+ (dongle 2).. Unresolved.
 == Car Scanner Pro (working) ==

@@ Line 212: / Line 212: @@
 | Rear right || AJ || AK
 |}
-Example: <code>Q*0.01627-0.344</code>. Letters must be upper case. Whether Torque accepts two-letter variables is ''unconfirmed''.
+Example: <code>Q*0.01372</code>. Letters must be upper case. Whether Torque accepts two-letter variables is ''unconfirmed''.
 === Known problem ===
 Using dongle 1 (generic Chinese ELM327-based) with Torque Pro on the XTRONS PX90, Torque read bytes <code>A</code> to <code>D</code> (first line of the reply) correctly, but every byte from <code>E</code> onward returned -1, even though a terminal received the full 102 bytes with the same commands. The start-command field is applied (adding <code>ATH1</code> changed the output). Tried without success: turning off "Faster communication", removing <code>ATS0</code>. Not yet tried: <code>ATAT0, ATSTFF</code> timeout settings, other apps, and the Veepeak OBDCheck BLE+ (dongle 2).. Unresolved.
 == Car Scanner Pro (working) ==
 Car Scanner Pro reads all the bytes where Torque Pro fails. Custom PID settings used:

@@ Line 159: / Line 159: @@
 Sensor IDs are specific to one car. Yours will differ.
-== Calibration (provisional) ==
+== Calibration ==
-Byte +6 against gauge readings:
+Byte +6 against gauge readings (bar). The five deflation-test counts were reconstructed from the app's displayed values.
 {| class="wikitable"
-! Raw !! Gauge
+! Raw !! Gauge (bar) !! Raw x 0.01372
 |-
-| 136 (rear left) || 1.868 bar
+| 136 (rear left) || 1.868 || 1.866
 |-
-| 131 (rear right) || 1.795 bar
+| 131 (rear right) || 1.795 || 1.797
 |-
-| 131 (front right) || 1.795 bar
+| 131 (front right) || 1.795 || 1.797
 |-
-| 128 (front left, start) || about 25 psi (from memory)
+| 126 || 1.73 || 1.729
 |-
-| 110 (front left, lowest) || about 21 psi (from memory)
+| 119 || 1.63 || 1.633
 |}
-Straight-line fit through these points:
+The last five rows are from one tyre during a slow deflation (assumed front left).
-* bar = raw x 0.01627 - 0.344
+* bar = raw x 0.01372
-* psi = raw x 0.236 - 5
+* psi = raw x 0.199
-The two front-left gauge values were remembered, not recorded, and most of the fit comes from them. Treat the equations as an estimate to be replaced by better data.
+No offset is needed, which suggests the byte holds gauge pressure. All points are within 0.004 bar except the lowest (0.027 bar off), which may be sensor update lag or slight non-linearity. More readings at low and high pressure are needed.
 == Torque Pro custom PIDs ==