[[Manual: Basics.Install.Mechanic]]
GND and GenBoard/Manual/DDFlyback are the most important things when playing with inductive loads, and several Ampere current. It's very easy to ruin hundreds (or thousands) EURO of equipments, and cause several days of extra debugging with bad (or lacking) connections.
Verify and measure every connection before powering up. Do NOT underestimate the importance of good grounding. Grounding well is cheap, but if doing sloppily, the learning price is high.
- all 4 GND5 (power-ground) pins must be connected to GND (EC36pin26) with short wires max 40cm (1.3 feet) from EC36 connetor to avoid damage caused by GND5 voltage jumping too high above GND (when ignition transformers, injectors or other loads are driven)
- EC36pin5
- EC36pin21
- EC36pin32
- EC36pin22 (assembled v3.x controller comes with EC36pin22 connected as GND5 ; it is recommended to do the same on customer-assembled controllers: connect EC36pin22 with a 0.5 .. 1mm2 wire to the GND5 near the IGBT-s; also short to EC36pin21)
- the sensors should be grounded to GND (EC36pin26) at the same point, or closer to EC36pin26
- sensors are grounded elsewhere would not ruin anything, but the signal would be noisy. Noise is unwanted and makes the VR trigger completely useless (engine won't start)
- after GND and GND5 are connected hard in the harness (some installers like to connect to a screw mounted on firewall; just make sure the screw doesn't come loose), the connected common-ground usually goes (with a thicker 1..2mm2 wire) to battery- (or other point can be OK).
as on MembersPage/PhatBob/UserGuide. Beware that insufficient instructions might be floating around (that required connecting GND and GND5 but allowed too long wires), use the above simple rules for safety of the controller; doing otherwise often results in several days of hunting for hard-to-track problems, avoid that.
Testing
- With ECM removed, on the EC36-wire connector, measure ohm between EC36-wire side GND5 pins (EC36pin5, EC36pin21, EC36pin32, EC36pin22) and the battery-. Must be very low, <=0.1 Ohm. Do this for all 4 GND5 connections.
- With ECM removed, on the EC36-wire connector, measure ohm between EC36-wire side GND pin EC36-pin26 and the battery-. Must be very low, <=0.1 Ohm
Why
- If all GND5 connections loose connectivity with GND (if they haven't been connected at all, or break due to a loose screw, or something) during engine (or WBO2) running, there is a huge problem, the board can be damaged.
- reasons to use many GND5 connections:
- if one breaks, HW will not be ruined
- high current capability of output drivers. Output current can be especially high with many low-z injectors and many ignition channels.
- GND and GND5 are not connected hard onboard v3.x (a weak, appr. 1 Ohm connection exist inside the TPIC6A259 aka. P259 chip)
- If GND and GND5 are connected hard onboard (eg. the GND-GND5 bridge that was applied for safety on unassembled v3.x until around 2005Q1 is not cut), the VR trigger signal can be noisy at very low RPM (cranking).
See MembersPage/PhatBob/UserGuide for ground hints and drawing.
See also