Megasquirt MS3 & MS3X Wiring Diagram
07-31-16, 10:57 AM
#2
Engine, Not Motor
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A few things I noticed:
-you'll need more than an 80A fuse to run your starter
-the rightmost fuel pump relay should have its coil powered by the switch IGN like the left most fuel pump relay
-your oil pressure, fuel pressure and oil temp sensors don't look to be connected correctly. 2 wire sensors will always need a bias resistor. But I'd expect the two pressure sensors to be 3 wire sensors, which would require 5V also.
-don't ground your wideband to the DB37. Ground it to the same ground point as the 'Squirt on the engine or ground block. The wideband draws too much current to ground through the ECU.
-try to avoid grounding your MS harness to both the chassis and engine ground. If for example the main engine ground was to fail, starter current would flow through the 'Squirt harness.
-you'll need more than an 80A fuse to run your starter
-the rightmost fuel pump relay should have its coil powered by the switch IGN like the left most fuel pump relay
-your oil pressure, fuel pressure and oil temp sensors don't look to be connected correctly. 2 wire sensors will always need a bias resistor. But I'd expect the two pressure sensors to be 3 wire sensors, which would require 5V also.
-don't ground your wideband to the DB37. Ground it to the same ground point as the 'Squirt on the engine or ground block. The wideband draws too much current to ground through the ECU.
-try to avoid grounding your MS harness to both the chassis and engine ground. If for example the main engine ground was to fail, starter current would flow through the 'Squirt harness.
08-01-16, 02:08 AM
#3
Adjustments
A few things I noticed:
-you'll need more than an 80A fuse to run your starter
-the rightmost fuel pump relay should have its coil powered by the switch IGN like the left most fuel pump relay
-your oil pressure, fuel pressure and oil temp sensors don't look to be connected correctly. 2 wire sensors will always need a bias resistor. But I'd expect the two pressure sensors to be 3 wire sensors, which would require 5V also.
-don't ground your wideband to the DB37. Ground it to the same ground point as the 'Squirt on the engine or ground block. The wideband draws too much current to ground through the ECU.
-try to avoid grounding your MS harness to both the chassis and engine ground. If for example the main engine ground was to fail, starter current would flow through the 'Squirt harness.
-you'll need more than an 80A fuse to run your starter
-the rightmost fuel pump relay should have its coil powered by the switch IGN like the left most fuel pump relay
-your oil pressure, fuel pressure and oil temp sensors don't look to be connected correctly. 2 wire sensors will always need a bias resistor. But I'd expect the two pressure sensors to be 3 wire sensors, which would require 5V also.
-don't ground your wideband to the DB37. Ground it to the same ground point as the 'Squirt on the engine or ground block. The wideband draws too much current to ground through the ECU.
-try to avoid grounding your MS harness to both the chassis and engine ground. If for example the main engine ground was to fail, starter current would flow through the 'Squirt harness.
Will change the pressure sensors, and have found the part in the manual for using the bias resistor for the temp sensor, will order one of these shortly.
Will make the other modifications as well that you mention, the grounding idea for the one return makes sense.
Last edited by orange; 08-01-16 at 06:49 AM.
08-01-16, 07:13 AM
#4
Revised Drawing
Have made a few modifications to the drawing, have changed my pressure sensors to 3 wire sensors as they should have been from the start.
Will solder the bias resistor to the MS3X for the 3rd temp sensor, will have to order this in first.
Attached is the revised drawing.
Will solder the bias resistor to the MS3X for the 3rd temp sensor, will have to order this in first.
Attached is the revised drawing.
Last edited by orange; 08-01-16 at 07:26 AM.
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