Due to the versatility of our products that can be used as ECU or TCU, the freewheel diodes cannot be installed like dedicated TCU systems. They are built into the harness. If you take level 1 harness or manufacture your own, then you must install these boards for the inductive loads. Especially if it is a PWM solenoid or a low resistance inductive load. Spitronics made it easy by supplying a little Diode board which is compact and can be included in the harness. If it is situated outside the car, care must be taken to seal the unit against water and dirt. You can put silicone on the board before shrinking the sleeve. Silicone will be forced between the components sealing them properly.

Below is an indication of how this board looks and the orientation of the diode stripes.

Warning: Make sure you use the correct board otherwise it will short the drivers damaging the TCU.

Above is a good practical way to solder the wires to the board. Split the sleeve of the wire without cutting it off. Then bend it sharply onto itself and solder on the I tabs. Make sure there are no shorts between the wires. See Option 2. You may also cut the wire and solder the other wire on the opposite pin from the diode. I1 to Q1 etc. Make this connection on the inside of the car if possible. See option 1. Note that the negative board gets a positive from the power relay pin 87 on R2+ point. We use the same boards for positive and negative drivers. Only the diodes are connected the other way round and the R2+ point is different.