MegaSquirt Guru's help
 

ok so the new board is in the car and its somewhat working, i can't get the car to start because of some problem.
i used this diagram for wiring
http://www.megasquirt.info/v22manual/extwir.gif

on the main relay i have pin 85 grounded, and i am not getting voltage to the megasquirt board, when that is not grounded i get just under 4.5v to the board. I don't want to try and turn the car over because i'm afraid if that isn't grounded it'll hurt something. I think this is the reason why i am getting a low voltage to burn the chip correctly.

so can anyone help me out

Re: MegaSquirt Guru's help
 

Ground it somewhere else, redo the connections so there is less resistance, or swap in a known good relay.

Re: MegaSquirt Guru's help
 

grounding it, even to the battery gives me 0v. when it is not grounded is when i get 4.5v the relay is new and the connections are great.

Re: MegaSquirt Guru's help
 

It sounds like completing the circuit between pins 86 and 85 is causing the relay to open instead of close. Do you have the other pins wired correctly?

Re: MegaSquirt Guru's help
 

i'm almost positive they are wired correctly, i've double checked them 3 times and my buddy 2. but it doesn't hurt to check again. i'll se what i can find

Re: MegaSquirt Guru's help
 

I apologize for my lack of confidence in troubleshooting this, as it's been a while since I've done much electrical work. I do have a Megasquirt, but it's not installed. :-[ It seems that this is a very basic application of a relay, and the relay isn't acting as it should. I still think you should try a different relay. Maybe just pull it from the ABS system or something else that can handle the same current load.

Re: MegaSquirt Guru's help
 

Hey, look a newb that knows something. :6

Re: MegaSquirt Guru's help
 

Quadruple check your wiring, and make sure you have good grounds. I followed that diagram and everything worked no problem. You can also swap the fuel pump relay with the main relay to see if the relay is the problem

Re: MegaSquirt Guru's help
 

alright, i checked the wiring, the relay and everything. I would check the grounds but like i stated before i get 4.5v when NOT grounded and 0V when grounded anywhere including the battery -. I traded out the relay for the ABS relay really quick, same thing happened.

Now this is more info i found while doing this. I have the power source for everything hooked up to the fuel pump, or where the fuel pump used to get power. I spliced that wire and its connected to the FP relay at pin 30 and the main relay at pin 30, like the diagram shows. from there i have a wire going from pin 87 to a fuse block, which is fused with (2) 5 amp fuses going to the injectors and another 5 amp fuse going to pin 28 on the DB-37. pin 85 on the FP relay is going to pin 37 on the DB-37 connector. Pin 86 on both relays is spliced together and connected to the original wire going to pin 86 on the FP relay. Now when pin 85 is grounded on the main relay i get little to no voltage (0v-2V) when the pin is not grounded it gets 4.5v which is still to low for me to burn a chip correctly

Re: MegaSquirt Guru's help
 

did you use a stimulator when building the board?

Re: MegaSquirt Guru's help
 

no i didn't use the stimulator, this problem has to be with in the wiring itself because not only am i getting the voltage reading out of megatune, but also at the connection to the fuse block and gronded to the battery.

Re: MegaSquirt Guru's help
 

This is getting slightly off topic, but here it goes. I bought a preassembled Megasquirt unit and tested it on my desktop computer. I used a power adapter from a cordless telephone to provide power. Have you ever had this unit powered on?

Re: MegaSquirt Guru's help
 

yeah its getting power in the car, i'm getting readings and everything from all the sensors. but when i try to burn the chip it says not enough voltage to burn safetly. which is where this problem comes in play. because with out burning the chip, the injectors aren't getting enought fuel to start the car.

Re: MegaSquirt Guru's help
 

I figured out the problem with the 4.5v and such but now i ave another problem
here is a picture i made of my wiring,



they only thing wrong with it is that pin 85 on the FP does lead to pin 37 on the Db-37 connector. I didn't see it go there before but i just went out and doubled checked it and it is going to the right place.

Now i have 12v to ms all the time even off, but also the FP turns on only turns on for a second or 2 after the car is turned onto ACC.(according to MS's LED's). The FP is not turning on during cranking, again noticed this by MS LED's that turn on when the FP is turned on.

Also the Injectors are not firing, according to the LEDS once again

but i did get the car to fire, and then die instantly

Re: MegaSquirt Guru's help
 

I know nothing about MS... But I am familiar with Hondas. If i understand you right your using the fuel pump circuit to power up your MS ECU? Have you considered that the fuel pump always cycles on at key on, to bring up the fuel pres.
If i remember my info correctly the fuel pump run signal after initial start cycle then comes from the ignition circuit (Dist).
What year and model is this caar??