ECU Grounding Issue- SR20

[leonb2004]

Hey guys. I currently have a S13 with a Blacktop S13 SR20 in it. My struggles first peeped their heads about 2 months ago. Randomly one day, the car wouldnt start. After 2 days of voltage testing, fuel pump and ignition testing, etc. the car finally started after removing the harness and putting it back in, and tightening it a little. Its ran fine ever since, until I recently brought my car down to install a FMIC and relocate the battery to the trunk. Never even touched the ECU or came close to it. Well, I get the FMIC isntall done and pressure tested, and I get the battery hooked up. Turn the key on, and everything lights up, power to everything. I go to crank, and it just spins over. Turn the key off, and back on, and it turns out my uber loud walbro isnt even priming. I mess with the ECU some more, remembering my past troubles, to no avail. So, I remove the cover on my ECU and dismount it. I take a test light to the inside of it, and start hitting the pins that connect to the circuit board. Well, I notice when I hit one of the pins, the pump primed and the ECU light came on. So I try to crank, nothing. I keep messing around with the test light, and cranking, and eventually it cranks. It runs GREAT after that. I drove it around town, boosting with the new FMIC, came back and parked it and tried to recrank. Nothing. I do the same thing to the same pin, and nothing. After 20 minutes of messing with the test light, it finally cranks. Ive also noticed my ECU under hood relay buzzing when I hit it right with the test light.

Ive tried checking every wire and connection I could find, but to no avail. Any ideas?

[drftwerks]

first youi shouldnt be using a test light with pins directly on the ecu, i tcould potentially damage the ecu internals, (unless low amp/current test light)

get a diagram, and find out exactly what relay is buzing.

need a little more precise info on what is happening.

[leonb2004]

The relay thats buzzing is the ECU relay. I swapped it with the fuel pump relay, and the relay in the ECU relay spot will still buzz from time to time.

And yes the test light is for low current applications, made specifically for computer motherboards and internals.

[leonb2004]

Any ideas anybody?

[drftwerks]

if you get me a wiring diag i can help more

[leonb2004]

http://www.innovatemotorsports.com/resources/1991_1995_Nissan_180SX_SR20DET.php

Theres an ECU pinout.

What I dont understand is why it runs fine once I get it to crank and get power to the ecu via the test light. Any ideas?

[drftwerks]

its not getting power on its own then, check the ecu fuse and assosiated wiring

[leonb2004]

Is there anyway it could be in the turbo timer wiring? The car came swapped and with a timer installed, so I dont know what went into it, but by the car running fine once its started, is it possible it could be in there? What should I do to inspect the wiring and what should I look for? Ive tried cranking with the timer and off. Does this make sense that it could be cranking while grounding a wire though?

[drftwerks]

jsut do what i said one post ago bro, if it runs fine if you give it power, and not on its own, wont it make sense that its not getting it on its own?

[leonb2004]

Well, I checked the ECU fuse and relay at the beginning of all this, and replaced the ecu relay. No luck. I removed the relay and testlighted the socket and Im getting power there. I checked my harness and I believe Im getting power TO the ECU via wiring, but the light isnt coming signifying the ECU has power. I only have to give the ECU a GROUND for the vehicle to start, after that its fine.

[drftwerks]

then BAM thats your problem, the ecu ground. it need POWER ANS GROUND TO OPERATE

???

[leonb2004]

Well, we checked grounds at the harness via multimeter, and all the grounds are properly grounded. I discovered when I ground out the Coolant Temp Sensor via test light, the pump primes. Could it be a bad CTS preventing the car from getting power to the ECU? =/