Power Issues

[fr335tyl3r]

Hey Guys,

Lots of crap below so a summary:

• Don't appear to have any switched power in the car anymore.
  Interior lights, clock, etc are working
  Popup motors are working but lamps are not
  Gauge needles do not move when switching ign on (expected they would move from their "off" positions)
  No power to ECU (power for relays is direct from battery, switching source is from the ign barrel)

Background story

Need a bit of help troubleshooting this problem - hopefully someone knows the answer relatively straight away as otherwise I'll be going off to test every point along the way for power in the car.

Some background on my situation. Car has been under build for about 7 months or so now, finally got up to putting power back through the car this afternoon. All seemed to be going well, connected battery and the interior lights came on (doors were open), and nothing seemed to go "bang", and as far as I can tell none of the fuses popped.

Thinking to myself all was sweet, I got into the passenger side, plugged the laptop into the ECU (Haltech) and proceeded to try and go into "online" mode -> ie, the mode where you modify stuff thats going on in the ECU. It doesn't let me connect - saying that the ECU was unable to be detected.

According to the manual this is either a problem with the cable, the laptop or the power to the ecu. Cable is brand spankers and the laptop has been used to tune other haltechs previously so it shouldn't be an issue with that.

I decided to muck around a bit and see if the power was actually everywhere it should be. Interior clock, etc was all going so I was thinking everything was good, but I turned the key over from "Off" to "Acc" and then "On" and I didn't hear either of the new relays click over (fuel and main power relay). Thought that was a bit odd -> Power for these relays is direct from battery through a fuse bank, and fuses are good, so it must be the switched source coming from the IGN barrel causing problems. Popped up the headlights, the motors are working, but the headlamps themselves did not turn on - no power getting to headlights. Also noticed that gauge needles do not move when you switch the ignition on, they stay in their "off" locations.

What could cause this? Ie, no switched power, no headlights, but everything else seems to be operating?

[Entaran]

How are your chassis earths?

I wouldn't bother checking anythign except the earths to begin with. Is your fuse bank earthed correctly?

[Starion VR4]

ok, there is a fuseable link hear where yr old air box is, in the wiring harness, have a look at that, nine was blowen just after i changed to MPI, had a short but didn't detect it untill it blew the link, if U need a pic will post 1. :beer

[fr335tyl3r]

Ok that was the dumbest problem ever. This is proof of why you should not start tuning the car when you have a ridiculous cold that causes you not to think straight.

I had NOT turned the key all the way to "On". It was still on "ACC" so no switched 12v was getting through. Went back this morning and all was fine. SIGH!

Problem #2 - I am blowing one of the new fuses as soon as the relay gets power (ie, switched voltage applied). The rail is the injector/sensor/ignitor rail, so I am working my way back trying to find out where the rail is grounding out...ignitors and injectors have been eliminated thus far...fingers crossed I don't have to pull the loom out.

[4g6beat]

i had similar trouble with mine yurns out it was the factory relay that primes the fuel pump. even though i had my own fuel relay for the ecu if orgot to remove the original one and it arced out intermitently when switching off the car. it's a little gold box located above the ecu it has about 6 wires going to it (well to a plug that comes from it). have a look if you've left it hooked up.

[fr335tyl3r]

Solved problem number 2 this morning. Turned out the O2 sensor positive had been wired to the O2 sensor signal, causing the fuse to pop its brains out as soon as power was applied.

Problem number 3 reared its head and we are working on diagnosing at the moment :D

[WANTSOM]

Who did the wiring?

[fr335tyl3r]

:x

who do you think?
sigh :(

It was a result of us rushing to get wiring finished and the only diagram we didn't have on hand was for the O2 sesnor, so we just had a guess at it. Apparently we guessed wrong.

[WANTSOM]

Ya lurn though hey :beer

[fr335tyl3r]

Indeed. As long as the ECU doesn't cook itself, I'm willing to wear a few "problems" as a learning experience. Ie, if i dont have to spend heaps more on fixing mistakes then I don't care :D

Luckily it was just fuses.