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Old 05-09-2013, 11:45 PM   #1
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Default MSPNP1 Serial Cable DIN Pinout. Need Help.

Hi everyone.

I have not yet needed to ask a question though out my entire megasquirt install. which involved installing a PNP9697 into my 90 with a 94 1.8litre.

But I am now stumped with this small issue.

All was going well and had the car fairly well tuned. Until my girlfriend yanked on the Serial cable into my laptop pulling the wires from the connector on the DB9 (computer end) of the cable.

I have searches for a few days and cant find any info.on the 4 pin connector socket on my megasquirt. Once I know the fuction.of these pins I can resolder the plug.

Which is RX which is TX??

Open the case there are four wires connected to the socket.

Red. Blue. Yellow. Green.

I have worked out Blue is ground.

Im guessing yellow and green are rx tx ( recieve and transmit data )

But im not sure.

I have tried

Blue to DB pin 5 ground.

Yellow to DB pin 2 RX

Green to pin 3 TX

red to DB pin 9 - no fuction.

However no connection.

This isnt a connection issue with settings and port numbers

I simply have my serial cable.wired.wrong.

Can some one please help.

A continuity test would be a simple answer.

or even a picture of the db 9 with the
. mind you these wire colors are different but may still help me.

Thanks in advance

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Old 05-10-2013, 12:32 AM   #2
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Even someone could measure the voltages from ground to pins 2 and 3 on their db9 plug on the seial cable.when plugged into the megasquirt but not the laptop.

I currently have.

8 volts DC on pin 2

and 5 Volts on pin 3

Im not sure what I should be seeing here.

If anyone needs any advice on changing ecu year models I can assist.

Please help me. My car is running lean judging from the plugs having white tips so I have no.way of.telling afr.
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Old 05-10-2013, 08:16 AM   #3
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I worked it out.

The pinout is as follows.

Color of wire.that connects to the rear of the 4 pin mini din plug connector
inside the ecu case. MPNP1 only.

Red wire - TX to DB pin 3.

Blue wire - ground - db pin 5

green wire - 5v supply for bluetooth. db pin 9

Yellow - RX. db pin2.


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