volumeking333

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


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

pin

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

volumeking333

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.

pin

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?

volumeking333

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

pin

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.

Darkelvis

Hey, look a newb that knows something.

Reddy

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

volumeking333

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

Reddy

did you use a stimulator when building the board?