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MegaSquirt 2 PNP wont connect

JMORGAN

New Member
Hello, I have a 1988 LX 5.0 AOD car which I have just installed the American Auto wire kit into. With this harness, I decided to purchase the Megasquirt2 PNP PCM. I cannot get it to connect to the laptop. I have their serial to USB adapter and cables and such. I tried to follow their no connection diagnosis process but it's a bit vague and led me nowhere. It states to check power first (duh) in which I should have 12 volts to the unit. which I do on the main wire (pin 1). But because it does not specify a pinout due to it being a Plug NPlayy (PNP) unit I used the factory pinout to follow my wiring.(see attached pinout) I don't think it's a unit problem but I don't know where I should be checking for voltage and expecting it. I'm going to check power at pins 1, 37, and 57 as well as the ground wires at pins 20, 40,50, and 16. The EEC relay supplies power to pins 37 and 57 when commanded to do so via the factory wire that went to the ignition switch. this wiring is no longer present so if it doesn't provide the power I may have to find an ignition source (key on) voltage and cut and bypass that relay as a whole. I have no idea what I'm doing. I'm not new to cars however I took on more than I could chew at once and am a bit overwhelmed. I'm looking for some advice and using this as a way to document my problems so that maybe one day someone else can use it to help them out.
88-91_5.0_EEC_Wiring_Diagram.gif
The next section of their diagnosis says to check the USB serial adapter and the port. essentially it says to check port data and change it. I've done both of those steps. downloaded the driver and have successful recognition of the port using their port scanner. the port Is recognized but again reads as no connection.(still have not checked the voltage on the above wires.)

This is where I am at during the diag process for this no connection. If anyone has had any experience with no connection and or has any advice I'd greatly appreciate it, This is my first time ever posting to a forum so thank you for all the help and advice.
 

347HO

Active Member
I see:
Pin #1 = 12vdc positive from batt
Pin #40 = 12vdc negative from batt
Pin #60 = 12vdc negative from batt

It appears all ground and power wires are slightly fatter (14ga).
Should make it easier to identify.

Is this megasquirt schematic?
 

JMORGAN

New Member
I see:
Pin #1 = 12vdc positive from batt
Pin #40 = 12vdc negative from batt
Pin #60 = 12vdc negative from batt

It appears all ground and power wires are slightly fatter (14ga).
Should make it easier to identify.

Is this megasquirt schematic?
No mega squirt does not provide a pinout as it utilizes the factory pinout. I managed to overlay and bypass the EEC relay providing a 12v supply to pins 37 and 57 which allowed the system to communicate. I had solved my own problem but as per usual. once you have one problem you find more. I'll create a new thread for my new issue : /
 
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