System Diagnostics

Jump to navigation Jump to search


The UZZ32 Soarers contain an on-board diagnostic system which will check key systems and return error codes which explain where the fault is. This section explains how it works, what systems are covered, how to enter each of the diagnostic modes and how to access the results. The Error Codes section contain further details including the definition of various error codes.

What systems are covered

The system can check components such as:

  • Engine
  • ABS & TRC
  • Active Suspension
  • Air Conditioning
  • 4WS
  • Automatic Transmission

How the system works

The system automatically watches for abnormal events (including, say, pressure being too low or too high), as well as - especially in Diagnostic Mode - things that should have occurred, but haven't (such as a wheel turning).

If a system failure occurs, the system will remember it and - if it happens again - store an error code.

In general, the troubleshooting process will be:

  1. clear any old error codes
  2. optionally, enter diagnostic mode for the relevant system
  3. test drive the vehicle
  4. capture error codes
  5. look up error codes
  6. determine the cause
  7. address problem areas

Toyota's system is proprietary

The OBD system used by Toyota on these vehicles is proprietary and unlikely to be read by most automated code reading devices. For example:

  • The inexpensive ODB-II readers available on eg E-Bay will not work on the UZZ32, even if an adaptor cable is used to "convert" the plug from Toyota's to the "standard" one.
  • Some OBD-I readers claim to be able to read Toyota codes and could potentially work with the UZZ32. However, these tools usually state that they work only with the engine system, and not with eg the ABS or airbag. They could potentially be tricked into reading "other" codes by jumpering the pins.

Clearing old error codes

To avoid unnecessary confusion by "old" error codes (that may no longer be occurring), it is generally advisable to clear any existing error codes before conducting a test.

The error codes are cleared when certain fuses (EFI 30A and Dome 10A) are removed, or when the battery is disconnected for at least 10 seconds.

How to enter diagnostic mode

The diagnostic mode can be entered either through the DLC or EMV.

Jumper the relevant DLC pins

To enter diagnostic mode, the DLC1 or DLC2 connector pins need to be connected correctly.

The available test modes include:

  • TS & TC connected to E1: ABS, SUS, 4WS, TRC, CRUISE, AIR BAG
  • TE1 connected to E1: EFI & ECT
  • TE2 connected to E1: conduct a more sensitive test mode
  • TC connected to E1: Brake
  • TS connected to E1: Suspension

Enter Diagnostic Mode through the EMV

Alternatively, holding the bottom left () and bottom right () buttons on the EMV simultaneously while turning the ignition switch from ACC-ON-ACC-ON-ACC is the equivalent of TC and E1. However, if the ignition is turned OFF or the engine is started, the test is cancelled.

Test drive

The service manual explains the detailed procedures to ensure the right sensors are triggered in each test mode, including eg:

  • accelerate
  • brake
  • turn
  • press various buttons as instructed
  • open door

In general these procedures are designed to ensure that the vehicle is driven so that relevant systems, sensors and controls are operated. Be sure to also exercise relevant buttons (eg suspension high, suspension off) as the system would otherwise report those as faulty

How to access the results

The results can be viewed through three different alternatives:

  • The EMV displays multiple test results simultaneously
  • The LCD panel on the dash displays test results one by one
  • By connecting a test light / LED to the DLC connector


The EMV is the most user-friendly but may not work for all test modes. Unlike the lesser feedback mechanisms, the EMV can report the date & time at which each error code last occurred.


If the EMV is not available, the LCD is the next best option. It will display, eg SUS OK or ABS NG. Press Scroll button to move to the next display, which could be eg ABS 51. Repeat until all errors have been captured.

LED test light

connect test light / led / volt meter between pins x and x. Then count the pulses.

Ie code 3 would be: - - -

And thirty three would be - - - - - -

If multiple codes are sent, there will be a longer gap between them.

Interpreting the test results

The first step is to look up the error code(s) and understand what the reported errors mean. If only one error is reported, there is a good chance that the problem really is in the reported area.

However, if multiple errors are reported, the cause of the problem may be less obvious. Eg if many suspension error codes are reported, it may simply indicate that the vehicle has not been driven, or that the suspension ECU is not working. The root cause might even be unrelated to the suspension. For example, an alternator failure will mean that the suspension ECU does not work...


Sources include: