Troubleshooting

Problems connecting to the ECU

Establishing the connection is the most critical part of a diagnostic session. If it doesn’t work immediately, try some of the suggestions below. Don’t give up prematurely; although such vehicles probably exist, I have not yet encountered a K/L or CAN passenger car that cannot be diagnosed with CASCADE.

K/L and baud rate

The most common problem when trying to contact a control unit via K/L interfacing is wrong data transmission speed. While in many cases the correct speed is known beforehand and will be selected automatically, in some cases it is not. The diagnostic software tries to measure the baud rate, which is a capability the FTDI chip has as well, but my experiments have shown these measurements to be extremely inaccurate. Therefore, in CASCADE you may have to manually set the baud rate until you find the one that is being used. Sorry about that.

So what speed should you use? In most cases, the speed is either 9600 or 10400 Baud. Mitsubishi vehicles often use 15625 Baud. If these rules of thumb don’t lead to success, you will have to experiment, or consult the Internet.

Non-standard pin assignments for K/L ECUs

Some manufacturers connect the K line of ECUs that are not part of the standard OBD2 diagnostics routine to pins other than the standard-mandated number 7. A common pattern in Hyundai and Mitsubishi vehicles seems to be to have the ABS system on pin 8 and the airbag on pin 12. If you cannot connect to an ECU, it may be connected to a non-standard pin. Unfortunately, that means you will have to physically modify your interface if you want to diagnose these ECUs. You would have to cut the lead to pin seven and reroute it to the correct pin, or you will have to fashion an adapter that allows you to jumper the K line to different pins.

To find out what pins the various ECUs are connected to in your vehicle, you will have to consult the wiring diagrams. You may be able to find free copies of those through realfsm.com. Be aware that connecting the diagnostic interface to the wrong pin may cause damage to your vehicle! Even though such damage will probably be limited to a blown fuse, it’s better to be safe than sorry.

Ignition toggling

Generally, all ECUs require you to turn on the ignition before you can connect and diagnose them. It is, however, important to know that many ECUs fall asleep if you don’t make a connection attempt within a certain time after turning the ignition on. In some cases, this time frame is in the order of a few seconds. If the connection attempt takes too long, e.g. because the diagnostic software has to try a few modes of communication before finding the right one, it may be necessary to turn the ignition on and off again while the connection attempt is in progress. This is quite tricky, and therefore CASCADE will attempt to assist you in it. When there is a good occasion to toggle the ignition, CASCADE will show the hint “Ignition off/on” in yellow in the hint box. This is not an accurate science, though, and you may be more successful toggling the ignition a bit earlier or later.

This issue seems to affect older vehicles more than more recent ones, but even vehicles with CAN bus diagnostics sometimes exhibit this behavior.

ISO-14230 (“fast init”) vehicles

There is a generation of vehicles that require use of the so-called “fast init” connection method, which relies on very accurate timing, to the order of a few milliseconds. While this might not sound very tricky given the speed of modern computers, the non-realtime nature of PC operating systems makes it so. In practice that means that even if everything (speed, pin assignment, ignition etc.) is correct, connecting to a “fast init” ECU can take a few tries, sometimes more, sometimes less, so don’t give up!

Mitsubishi peculiarities

Older Mitsubishi vehicles have to be coerced into diagnostic mode by wiring pin 1 of the OBD connector to ground. I have observed this on a 1997 Mitsubishi Colt ECU. On the other hand, a 2005 Mitsubishi Lancer did not require any such tricks. I suspect that this peculiarity is limited to pre-OBD2 vehicles.

Problems on the PC side

Interface problems

If you cannot connect to your car, the “iface” indicator stays off and the “Interface” box keeps saying “none”, one of the following things could be wrong:

  • No interface plugged in. You need to have a supported K/L or K+CAN 1.4 interface with FTDI chip connected to your computer via USB.
  • No FTDI drivers installed. You have to download the drivers from FTDI and install them. This step may have been performed automatically if you are using Windows 7.
  • You are using an incompatible interface. Make sure your interface uses an FTDI USB-to-serial converter and is connected via USB.

 

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