Troubleshooting the MegaJolt Lite Jr.
- 1 Configuration software compatibility
- 2 Hardware Troubleshooting
- 3 MJLJ communicates with Configuration software; No RPM signal
- 4 MJLJ Communicates with PC; Does not control advance
- 5 Problems with USB-Serial Adapters
Configuration software compatibility
If you see an error message while attempting to communicate with the MJLJ, such as 'Could not open port' or 'Timeout reading runtime data' you can use a terminal program to directly test the MJLJ unit.
Here are the instructions for this testing procedure, using the common 'Hyperterminal' software.
Troubleshooting with Hyperterminal
Open up Hyperterminal. create a connection, and configure it to connect directly to the COM port you are using for the MJLJ.
When it asks for the communication settings, use the following:
Bits Per Second: 38400- for MJLJ V4 hardware, or 4800 - for V3 MJLJ hardware Data Bits: 8 Parity: None Stop Bits: 1 Flow Control: none
When you get to the main screen, send a capital 'C' to the controller. you won't see what you type echoed on the screen, but the controller should 'reply' with what looks like a sequence of random data. This simulates the Configuration software requesting the controller's current configuration
Pressing 'S' returns the current runtime status; You will see only a few random characters displayed.
If the above does not work, or if Hyperterminal indicates a COM port or communications error:
- Use a different serial cable. The cable you're using might not be compatible serial cable, or may have a broken internal connection.
- Are you using the same serial port with other applications? Programs like synchronization software for hand-held devices like the Palm are known for keeping the serial port open, preventing other applications from accessing it.
- As a debugging step, try a different computer. This will at least let you know the MJLJ and software can communicate, and will help narrow down the source of the problem.
- If you're using a USB-serial adapter, make sure the latest drivers are installed, the driver shows no errors, and you know which COM port it was installed on. Often the USB-Serial adapter will install on a high COM port number, like COM6. You can verify this by accessing 'Device Manager' in Windows and viewing the properties of the USB-Serial adapter under 'Ports'.
If you can get the expected response from the MJLJ, then there is a configuration problem with the MJLJ software. Verify you have the correct COM port set under 'Options'. If the trouble persists, check for a newer version of the software, or inquire on the forums for additional help.
If you built the MJLJ from a kit and your controller does not communicate or otherwise doesn't seem to be 'alive', perform the following checks;
- Verify you have an adequate power supply, correctly connected to the MJLJ unit. See the Vehicle installation guide
- With the unit powered up, check to make sure the correct voltage (+5v) is present at all of the power input pins of the integrated circuits and oscillator.
Ensure sure the components are installed correctly
- Diodes and capacitors installed with the correct polarity (capacitors marked with a '+' or '-' sign)
- Integrated circuits, oscillator and transistors with the correct polarity (orient the notch on the chip with the notch shown on the circuit board)
Check for good solder joints
- Carefully inspect the pins to make sure the solder connections are bright and flow completely around the pins and onto the pad.
- Ensure that you haven't accidentally lifted the pad away from the board and broken a solder trace.
- Check for solder 'bridges' where you might have solder across two pads, resulting in a short circuit.
MJLJ communicates with Configuration software; No RPM signal
If you can communicate with the MJLJ software but cannot get an RPM signal from the EDIS module-
- Check the connection between the EDIS module and the MJLJ. Ensure the PIP signal from the EDIS module is connected to the correct pin on the Molex connector. Review the MJLJ connection diagram for your version of MJLJ hardware.
- Check the Molex connector itself, specifically that the pins in the connector are properly seated. If they are not pushed far enough into the plug, they can fail to make an internal connection at all, or intermittently.
- Perform the Hardware check in the Hardware Troubleshooting section.
- If you have access to an oscilloscope, you can verify the PIP signal on Pin 4 of the processor.
- You can also check the PIP signal using the AC setting of a multimeter. with the engine running you should see an AC reading that goes away when the engine is not running.
- Feel free to inquire on the Forums
MJLJ Communicates with PC; Does not control advance
If you can communicate with the MJLJ, but cannot get the MJLJ to control the EDIS module (i.e. you have connected a timing light and cannot observe the ignition advance changing), verify the following:
- Verify the MJLJ sees the PIP signal emitted from the EDIS module. The best way to verify this is to observe the realtime display, watching for RPM changes.
- If the configuration software shows an RPM reading, check the connections for the SAW signal, verifying that it is connected correctly. If you have an oscilloscope, watch for the SAW pulse coming from the MJLJ module; otherwise, watch for an AC signal using a volt meter.
- Check your wiring. Ensure you are connecting to the correct pins on the MJLJ molex connector and the EDIS module.
- Finally, inquire on the Forums.
Problems with USB-Serial Adapters
Communication stops when engine is running
See our USB-Serial adapter information page for extended information on USB-Serial adapters.