[MSII, 3.0, v2.88, MT2.51, via Relay board]
I wanted to create a circuit on the Proto Area to use the Spare port for the Knock Sensor to control the +5V source required to an HEI distributor.
(I'm using the FIDLE to control Fans and am running an IAC & Ignition Control)
I've set up the circuit below on the Proto Area which as well as providing control over 'when' MS takes over Ignition control also lights up an LED when output is 0V (ie HEI module in control of Ignition during cranking)
I've run the +5V output to Spr4, Pin6 and with some previous mods to my relay cable and relay board (See Relay forum for MSII Mods) I've now pulled this controllable 5V source out into my wiring loom via the relay board.
I've seen a lot of questions on the forum re this subject so though I'd post a complete schematic of my modification.
James
+5V to HEI - controlled by Spare Ports - Solution
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
+5V to HEI - controlled by Spare Ports - Solution
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MSII v3.0, 2.xx MT, LC-1
The GM HEI distributor requires a +5V source into pin B.
If Pin B = 0V then the HEI module control timing (ie during cranking), when set at +5V the ignition contol passes over to Megasquirt.
There are a lot of ways to set this up, you can:
>Set a seperate relay up external to MS to switch from a 'hot on run but not crank' source to switch the TPS +5V source on/off.
> If your using the Relay box you can set the Fidle relay to do the same (if your not already using it) with a jumper to a 5V source and setting up the spare port options.
> You can (now) set pin B permanently at 5V from the TPS source and use MS to control Ignition during cranking (see MegaManual for set up options on this one).
> You can modify MS to use one of the three LED driver transistors in MS to act as a switch using a 5V pullup resistor.
> Or you can set up a seperate switch (as above) to do the same using another 'spare' output (ie Knock).
I chose to impliment the above as I am using the Fidle relay to drive fans, I didn't want to introduce a seperate relay to my loom and I wanted to use the HEI module rather than MS during cranking.
James
If Pin B = 0V then the HEI module control timing (ie during cranking), when set at +5V the ignition contol passes over to Megasquirt.
There are a lot of ways to set this up, you can:
>Set a seperate relay up external to MS to switch from a 'hot on run but not crank' source to switch the TPS +5V source on/off.
> If your using the Relay box you can set the Fidle relay to do the same (if your not already using it) with a jumper to a 5V source and setting up the spare port options.
> You can (now) set pin B permanently at 5V from the TPS source and use MS to control Ignition during cranking (see MegaManual for set up options on this one).
> You can modify MS to use one of the three LED driver transistors in MS to act as a switch using a 5V pullup resistor.
> Or you can set up a seperate switch (as above) to do the same using another 'spare' output (ie Knock).
I chose to impliment the above as I am using the Fidle relay to drive fans, I didn't want to introduce a seperate relay to my loom and I wanted to use the HEI module rather than MS during cranking.
James
MSII v3.0, 2.xx MT, LC-1