On board diagnostics

OBD2 connector (plug)

Like all cars, the Elise is fitted with an On board diagnostic, or OBD, connector (socket) tucked away in the passenger foot well.

This can be used to communicate with the cars ECU for retrieving diagnostic information, resetting the MIL or viewing live engine parameters.

NOTE: This is only valid for the Elise S2/Exige S2. The Elise S1 and Exige S1 is equipped with a similar connector, but this connector is NOT OBD compatible!

The standard is also referred as: -

• OBD2
• OBD-2
• OBDII
• OBD-II

In europe the standard is called: -

• E-OBD
• EOBD

In practice it's very close to the USA-based OBD2 (J2534) standard and most OBD2 scanners will work. The meaning of some of the codes in EOBD are slightly different from OBD2 though.

Port Location

Evora

On a cable that hangs down under the dash on the drivers side or (passenger side on left hand drive cars).

Fixed to the aluminium crossmember, pointing down, just past the point where the dash leather stops in the footwell, you should be able to feel it without stretching forward too much from the driving position.

DIY

OBDII Connector, S2 111R

OBDII Connector, S2 Exige

On the S2 Elise it is quite simple to connect to the cars ECU yourself.

Until 2008 all S2's can be queried using the ISO 9141-2 OBD II protocol for the OBD required error codes and results. From 2008 onwards CAN is the only permitted OBD2 protocol.

All S2 variants also have a CAN bus connection on the same diagnostic connector.

For the Rover powered S2 variants the CAN bus is only connected to the engine ECU and used by the Lotus scan tool to reflash/upgrade the ECU and obtain the ECU dump information at the first service.

The dash unit still uses discrete inputs for the various gauges and information readouts, either connecting directly to sensors or using PWM signals from the ECU.

The Toyota powered S2 (111R, Fed-Elise, Exige2) also connects the CAN bus (running at 1 megabit/s) to the dash unit and does away with most of the discrete inputs to the dash unit, RPM, speed, MIL/CEL, coolant temperature and fuel level are supplied via the CAN Bus, the rest are discreete inputs.

The ScanTool3 provides the ECU reflash and DUMP via the K line, using the L line as an enable latch, the CAN bus is not used for reflashing or ECU dump, though it can be used by Lotus with their internal EFi supplied mapping tools.

Lotus has a tool called Lotus 20/20. What Lotus 20/20 can do...

Read general vehicle data** — It displays ECU (engine-control unit) information: part numbers, emissions-related data, VIN, and other core vehicle metadata. Read and clear diagnostic trouble codes (DTCs)** — You can scan all vehicle systems (engine, transmission / TCU, ABS, SRS/airbag on many models) for fault codes, and clear them. Flash / program certain control units** — For supported cars (most 2007+ Lotus, with exceptions), you can re-flash or update firmware/software for at least the Engine Management System (EMS), Transmission Control Unit (TCU), and ABS. Adjust some configuration via instrument pack (on supported cars)

Limitations / What it doesn’t reliably do (or may depend on model/access level)

• The version available to consumers/enthusiasts (“Independent Retailers” licence) is **limited** compared to the full dealer version.
• It apparently **does not support live data streaming** (e.g. reading live sensor data like transmission temperature for maintenance)
• Some modules (for example SRS/airbag) may use different communications protocols (e.g. K-Line rather than CAN), which could make them harder to access depending on adapter and vehicle model.

What you need to run 20/20

• A Windows-based laptop + a **J2534 pass-through adapter** to connect to the car’s OBD-port
• A valid Lotus-issued licence/subscription key — software won’t run without it.

🧰 Typical Use Cases

• Clearing fault codes after maintenance or repairs.
• Flashing updated firmware/software for EMS, TCU or ABS (e.g. after parts replacement).
• Checking VIN, part numbers, emissions data — useful for verifying the vehicle’s configuration.
• Adjusting some vehicle configuration bits.

OBD-II codes

OBD-II codes consist of a number of parts. Here is a sample OBD2 code:

P0171

Here is a breakdown of what each digit of the code means:

First Character - System The first character identifies identifies the system related to the trouble code.

P = Powertrain

B = Body

C = Chassis

U = Undefined

Second Digit - Code Type The second digit identifies whether the code is a generic code (same on all OBD-II equpped vehicles), or a manufacturer specific code.

0 = Generic (this is the digit zero -- not the letter "O")

1 = Enhanced (manufacturer specific)

Third Digit - Sub-System The third digit denotes the type of sub-system that pertains to the code

1 = Emission Management (Fuel or Air)

2 = Injector Circuit (Fuel or Air)

3 = Ignition or Misfire

4 = Emission Control

5 = Vehicle Speed & Idle Control

6 = Computer & Output Circuit

7 = Transmission

8 = Transmission

9 = SAE Reserved

0 = SAE Reserved

Fourth and Fifth Digits These digits, along with the others, are variable, and relate to a particular problem. For example,a P0171 code means P0171 - System Too Lean (Bank 1).

See Also

http://forums.seloc.org/viewthread.php?tid=112517 https://wiki.seloc.org/a/Lotus_20/20_diagnostic_Software

External Links

General Information

http://www.kbmsystems.net

http://en.wikipedia.org/wiki/On_Board_Diagnostics

http://www.obdii.com/obdii.asp

Vendors

http://www.scantool.net/

http://www.obdkey.com/

http://www.vitalengineering.co.uk/