Antenna Coil Open / Short (B2784)
The transponder key coil is built into the transponder key amplifier and receives a key code signal from the transponder chip in the key. This signal is amplified by the amplifier, then it is output to the transponder key ECU assembly.
DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
B2784 |
Antenna coil is open/shorted. |
|
CAUTION / NOTICE / HINT
NOTICE:
If the transponder key ECU assembly is replaced, register the key and ECU communication ID (See page .gif)
).
PROCEDURE
READ VALUE USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Body Electrical / Immobiliser / Data List.
(e) Read the Data List according to the display on the Techstream.
Immobiliser (Transponder Key ECU Assembly)Tester Display | Measurement Item/Range | Normal Condition | Diagnostic Note |
|---|---|---|---|
Antenna Coil Status |
Transponder key amplifier coil condition/Normal or Fail |
Normal: Antenna coil normal Fail: Antenna coil malfunctioning |
- |
OK:
On the Techstream screen, the item displays Normal according to the chart above.
| OK | .gif) | REPLACE TRANSPONDER KEY ECU ASSEMBLY |
|
.gif)
CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU - TRANSPONDER KEY AMPLIFIER)
(a) Disconnect the transponder key ECU assembly connector.
(b) Disconnect the transponder key amplifier connector. |
 |
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection | Condition | Specified Condition |
|---|---|---|
D22-4 (TXCT) - D21-5 (TXCT) |
Always |
Below 1 Ω |
D22-5 (AGND) - D21-7 (AGND) |
Always |
Below 1 Ω |
D22-14 (VC5) - D21-1 (VC5) |
Always |
Below 1 Ω |
D22-15 (CODE) - D21-4 (CODE) |
Always |
Below 1 Ω |
D22-4 (TXCT) - Body ground |
Always |
10 kΩ or higher |
D22-5 (AGND) - Body ground |
Always |
10 kΩ or higher |
D22-14 (VC5) - Body ground |
Always |
10 kΩ or higher |
D22-15 (CODE) - Body ground |
Always |
10 kΩ or higher |
D21-5 (TXCT) - Body ground |
Always |
10 kΩ or higher |
D21-7 (AGND) - Body ground |
Always |
10 kΩ or higher |
D21-1 (VC5) - Body ground |
Always |
10 kΩ or higher |
D21-4 (CODE) - Body ground |
Always |
10 kΩ or higher |
*1 |
Front view of wire harness connector (to Transponder Key ECU Assembly) |
*2 |
Front view of wire harness connector (to Transponder Key Amplifier) |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
INSPECT TRANSPONDER KEY AMPLIFIER (POWER SOURCE AND GROUND)
(a) Reconnect the transponder key ECU assembly connector.
(b) Reconnect the transponder key amplifier connector. |
 |
(c) Measure the voltage and resistance according to the value(s) in the table below.
Standard Voltage:
Tester Connection | Condition | Specified Condition |
|---|---|---|
D22-14 (VC5) - Body ground |
No key is in ignition key cylinder |
Below 1 V |
D22-14 (VC5) - Body ground |
Key is in ignition key cylinder |
4.6 to 5.4 V |
Standard Resistance:
Tester Connection | Condition | Specified Condition |
|---|---|---|
D22-5 (AGND) - Body ground |
Always |
Below 1 Ω |
*1 |
Component with harness connected (Transponder Key ECU Assembly) |
| OK | | REPLACE TRANSPONDER KEY AMPLIFIER |
| NG | | REPLACE TRANSPONDER KEY ECU ASSEMBLY |
Test yourself
A quick Toyota Venza quiz: every answer comes with an explanation and a link to the manual page.