megasquirt not connecting?

[ThatOneEuroE30]

So I have a MS2 built by SSSquid I put it in my car reconnected the battery hooked my laptop up to it and turned the ignition on and nothing happened as far as being able to connect to it. He installed some LED's on it to show when its got power and nothing is lit up. I haven't touched any wiring except for the ground thats on the engine loom i moved it back thinking maybe it was in a bad spot and still nothing. I left my DMM at home so couldnt check for power and ground at the connector but I don't think its the issue cause i was driving the car a couple weeks ago no issues and all I did was unplug the stock ecu and plug the MS in to check and see if it was pre loaded with a tune.

[vtechnik]

Are you using a usb to rs232?

[ThatOneEuroE30]

Are you using a usb to rs232?

So I was able to get the MS unit to connect to my laptop when I plugged in a 12v dc adapter. How ever my car will not power on the MS unit I put the stock DME in the car and it all worked so I know the harness is good to go. I just pulled my MS board out of the case and I found that there is a wire going from the S3 terminal on the MS board but isn't soldered to the 55 pin board anywhere. I also noticed that for the main relay points on the board I have the output going to pin 36 which lines up with the wiring diagram but then I have the input going to 27 which I would think would be 37 per pin out diagram. It says that 27 is the ignition input for an OBC car but mine is not so I think I need to switch the 27 wire to 37? and find the home that the S3 terminal wire belongs too.

[rturbo 930]

I had a similar problem. Try it with your TPS unplugged.

https://www.miataturbo.net/megasquir...not-car-76659/

Last two posts, #5, and #6.

[ThatOneEuroE30]

I had a similar problem. Try it with your TPS unplugged.

https://www.miataturbo.net/megasquir...not-car-76659/

Last two posts, #5, and #6.

i have. the tps wires needed to be extended and I hadn't done that yet when i first tried. I's now a matter of now power within the MS unit it self. I found the main relay on the board to be going on pin 36 and 27 which is fine for a OBC car but mine is none OBC square connector so I'm 99% sure i need to be pin 36/37 so switched my pin 27 wire. I still need to find a home for the grey wire not connected to anything

[Andre3127]

The switched power pin from motronic header is only active when motronic switches the main relay when it receives the ignition signal. Try running megasquirt with the 30 and 87 pin (further one from 30, there are two) jumped.

[McGyver]

I would have assumed that a PNP unit would already have the Main Relay trigger taken care of, but maybe not.

The 2nd post discusses the Main Relay Trigger mod.

The 3rd post has some useful wire diagrams (specific to my install).

The 6th post has more info on the Main Relay Mod.

https://www.r3vlimited.com/board/for...ild-and-wiring

Hope that helps!

[ThatOneEuroE30]

I put a jumper wire on the main relay connector from terminal 30 to 87 on main relay connector when I did this the MS unit powered on since terminal 30 is always hot the key wasnt needed on. So this tells me that pin 37 on the board is not getting power which in turn powers the rest of the board. A thought I had but I'm unsure of, is take a wire for the second pin 27 terminal on the 55 pin adapter board and wire it one of the three 12v inputs on the board it self. One of the inputs already has a wire going from it to pin 37 however its clear voltage isnt getting that far. So maybe pin 27 to the 12v input would then send power to pin 37 activating terminal 87 on the main relay allowing it to turn on or would it just instantly turn on once power hits it from pin 27 rendering pin 37 useless.

[McGyver]

I put a jumper wire on the main relay connector from terminal 30 to 87 on main relay connector when I did this the MS unit powered on since terminal 30 is always hot the key wasnt needed on. So this tells me that pin 37 on the board is not getting power which in turn powers the rest of the board. A thought I had but I'm unsure of, is take a wire for the second pin 27 terminal on the 55 pin adapter board and wire it one of the three 12v inputs on the board it self. One of the inputs already has a wire going from it to pin 37 however its clear voltage isnt getting that far. So maybe pin 27 to the 12v input would then send power to pin 37 activating terminal 87 on the main relay allowing it to turn on or would it just instantly turn on once power hits it from pin 27 rendering pin 37 useless.

hey man so im mulling over my board and on the wiring diagram for the car. Pin 18 is the constant 12v input for the dme so it has power to move around and trigger the main relay. On my board I have zero wires on the pin 18 adapter for the 55 pin. I have one wire going from the 12 source to pin 37 but no constant 12V wiring going into that for an input. see pics

Here is the DIYAutoTune info:
https://www.diyautotune.com/product/...-bmw-e30-325i/

https://www.diyautotune.com/support/...oard-assembly/

First, this is how the stock wiring works:
For a late model car (look up your specific Electrical Troubleshooting Manual [ETM], save the pdf before they disappear!), Sheet 1360-6 shows how power is supplied to various systems. The stock DME has constant 12v on Pin 18. This probably allows the DME to store codes and other functions. Sheet 1360-4 shows that when the key is in Run or Start, signal is sent to the DME Pin 27. Sheet 1360-6 shows power going to Pin 86 of the Main Relay. When the DME sees a signal on Pin 27, it provides a ground on DME pin 36 (connected to Pin 85 of the Main Relay). The DME Pin 36 ground closes the Main Relay control circuit, triggering the relay. Now the power going into Main Relay Pin 30 is connected to Main Relay Pin 87, providing power to the ABS System, Injection Electronics, Fuel Pump Relay Pin 86, and the DME on it's Pin 37.

General MegaSquirt:
MegaSquirt needs a switchable power input so that you can reboot and so it isn't running 24-7. This can be accomplished in many ways, but page 14/201 of the Hardware MegaManual shows using a key to control the control circuit of a "main relay". This provides power from the battery, through a 3A fuse, to MS Pin 28. You need a fuse so you don't fry MS.

Your Car:
From what I can gather, you have DME Pins 27 (start switch) and 36 (Main Relay ground) connected to Relay 2 trigger on your main board. The OUT pin (DME Pin 36) is grounded when voltage is applied to the IN Pin (DME Pin 27). So when you turn the key, it should power the Main Relay Control Circuit, triggering the relay. This provides power to DME Pin 37, which is used to power MS Pin 28 (MS power input).

You say that you're not getting 12v on DME Pin 37. I would start by turning the key and checking that you have:
- before anything, test your relay by applying +12v to pin 86 and GND to pin 85. Verify continuity across pins 30->87
- +12v at Main Relay Pin 86 (should be with and without turning the key)
- +12v on DME Pin 27
- +12v at the Relay 2 IN
- ground at Relay 2 OUT
- ground at DME Pin 36
- ground at Main Relay Pin 85
- +12v on Main Relay Pin 87
- +12v at DME Pin 27
- +12v ay MS Pin 28

Somewhere in that troubleshooting you should find your problem.


*side note: I like this setup and am going to copy it for my install so MS isn't powered directly from the key*

[ThatOneEuroE30]

Special thanks to mcgyver for sitting on the phone with me for 45 minutes as we trouble shot. We figured it out. I had a bad ground going from pin 2 to the ms board.moral of the story add as many grounds as you can. Never have too many. that was my only one and it failed.

[McGyver]

Special thanks to mcgyver for sitting on the phone with me for 45 minutes as we trouble shot. We figured it out. I had a bad ground going from pin 2 to the ms board.moral of the story add as many grounds as you can. Never have too many. that was my only one and it failed.

I wanted to type up some more info on this in case anyone else has a similar problem. I'm using the 1989 325i ETM for all of my pin-outs and wire diagrams. "ECU Pin" is the same pin number as the "Bosch 55-Pin" pin number.

First, this is a MegaSquirt Plug-N-Play (DIY PNP v1.5B) for an car running Bosch Motronic 1.1 or 1.3 (the 55-pin type ecu). This type of MegaSquirt uses a MicroSquirt module on the PNP board, which is jumpered to an Bosch 55-Pin adapter board.

Per Sheet 1360-0, turning the key to start/run supplies power to ECU Pin 27. OP's MegaSquirt takes this power and connects it to Relay 2 In (transistor's base). Once Relay 2 In has power, Relay 2 Out has a ground signal (transistor's collector). This is because the transistor's emitter is wired to a MegaSquirt ground. The ground from Relay 2 Out is connected ECU Pin 36, supplying a ground to the Main Relay Control Circuit (triggering the relay). Sheet 1360-1 shows that once the Main Relay is triggered, it provides power to ECU Pin 37. This is connected to MegaSquirt's power input on Pin 28, turning on MegaSquirt.

Only one of OP's MegaSquirt grounds was connected, which was to ECU Pin 2. OP tested ECU Pin 2 and didn't get a ground through his engine harness. No ground meant that the Main Relay never got triggered, and never sent power to MegaSquirt. That's why MegaSquirt was able to power up when he jumped the relay.

Per the 1989 325i ETM, on Sheet 0670-12, the stock engine wiring harness has grounds on the 55-Pin connector at pins 2, 14, 19, & 24. OP connected more of the engine harness grounds, when solved his problem. (Although he still needs to fix the bad ground in his wiring harness going to ECU Pin 2.)

[ThatOneEuroE30]

I wanted to type up some more info on this in case anyone else has a similar problem. I'm using the 1989 325i ETM for all of my pin-outs and wire diagrams. "ECU Pin" is the same pin number as the "Bosch 55-Pin" pin number. First, this is a MegaSquirt Plug-N-Play (DIY PNP v1.5B) for an car running Bosch Motronic 1.1 or 1.3 (the 55-pin type ecu). This type of MegaSquirt uses a MicroSquirt module on the PNP board, which is jumpered to an Bosch 55-Pin adapter board. Per Sheet 1360-0, turning the key to start/run supplies power to ECU Pin 27. OP's MegaSquirt takes this power and connects it to Relay 2 In (transistor's base). Once Relay 2 In has power, Relay 2 Out has a ground signal (transistor's collector). This is because the transistor's emitter is wired to a MegaSquirt ground. The ground from Relay 2 Out is connected ECU Pin 36, supplying a ground to the Main Relay Control Circuit (triggering the relay). Sheet 1360-1 shows that once the Main Relay is triggered, it provides power to ECU Pin 37. This is connected to MegaSquirt's power input on Pin 28, turning on MegaSquirt. Only one of OP's MegaSquirt grounds was connected, which was to ECU Pin 2. OP tested ECU Pin 2 and didn't get a ground through his engine harness. No ground meant that the Main Relay never got triggered, and never sent power to MegaSquirt. That's why MegaSquirt was able to power up when he jumped the relay. Per the 1989 325i ETM, on Sheet 0670-12, the stock engine wiring harness has grounds on the 55-Pin connector at pins 2, 14, 19, & 24. OP connected more of the engine harness grounds, when solved his problem. (Although he still needs to fix the bad ground in his wiring harness going to ECU Pin 2.)

And i believe i got it fixed. Now getting continuity from the pin to the chassis. Only other thing is maybe the wire that was soldered. In was a bad bit of wire.