Can't fire up. Buzzing from the relay, lamps blinkin- HELP

[mrgud]

ok, after few days of rest, here is the bump up...

No, we did not fire the car up, and no, we did not fix the problem with the electric system...

- checked and changed all relays, in the engine bay, in the interior, even the ones around the ECU- NO GO... everything the same...
- checked the efi- the 1/4 of Hachi that I got for parts had the ECU on it. The man I boughtr that hunk of garbage said that before he sold the engine and tranny he the buyer fired up the engine, so that ECU is fine... Connected that one instead of mine- still the same...
- checked all fuses on the car (took them down and checked them with the unimer- a friend said that the fuse can be false(broken or out of order even if it looked good)- all fuses fine...
- checked the mass of the car, visualy checked the cables, of the ground
- checked the conection on the main conector in the engine bay (the one on the firewall abowe the engine...)

- than Meshin started measuring and checking the power on the fuse box in the engine bay... One by one fuse out and checked the conector. He found that the fuse conector has curent on both pins... It is suposed to have curent only on one- 12V, the other must be 0. This one had 12 and 10 V on it... (I believe it was the EFI fuse)
- so- the fuse was fine, but it had curent on both pins (ground and +)- obviously there is some electricity brake-away somewhere, some wire is loos or something burned and short-cutted it self...

- checked the ignition switch on the ignition key (behind the ignition lock)- by the scheme in the manual- AyOkay- not burned, and funktional...

- now- there is something wrong around the fuse box in the engine bay or somewhere between the ignition key lock, the fuse box in the car and the fuse box in the engine bay...

As Mao Tse-Tung said once: "Even a kick in the ass is a step forward!"

I still don't know what is wrong- but I'll find out... and when I do, call me "the Hachi exorcist guru"!!
Offcourse, if somebody has the faintest idea what the hell is wrong, please, express your opinion...

(HINT: these are the simptoms, in short;
- when the batery is conected, you turn the key to acc- one of the relays in on the fusebox in the interior buzzes and the check engine and batery lamps glow slightly, turn the key to give contact - check engine lamps goes off, you have only the batery lamp. Chranck the car it crancks but still check engine lamp is of... turn the key off again, the relay buzzes the 2 lamps glow slightly again... )

[meshin]

mrgud Wrote:- than Meshin started measuring and checking the power on the fuse box in the engine bay... One by one fuse out and checked the conector. He found that the fuse conector has curent on both pins... It is suposed to have curent only on one- 12V, the other must be 0. This one had 12 and 10 V on it... (I believe it was the EFI fuse)

EFI fuse ... Voltage on contact on one pin is 12V, on other pin is 10V.

We checked the same thing on my car (AE82 4AGE) and voltage on one pin is 12V, on other pin is 0V.

[Ivan141]

follow the wires...see what you come up with.. have a look in the factory manual to get an idea where the wire goes to. If it's a short-circuit you'll have to track it down.

[Red]

The schematic will be *necessary* to pin that one down. The EFI fuse goes to the EFI main relay but a failure downstream of that in all sorts of places could put voltage on that line. Fuel pump circuits, computer (if it was attached while the quarter was cut out, it might be damaged), fuel pump test connector or check engine connector if they were shorted out...it hurts to look at. Some time with an LED test light or multimeter is going to be the way to find out where that 10v is coming from.

[Knudsen]

mrgud Wrote:- than Meshin started measuring and checking the power on the fuse box in the engine bay... One by one fuse out and checked the conector. He found that the fuse conector has curent on both pins... It is suposed to have curent only on one- 12V, the other must be 0. This one had 12 and 10 V on it... (I believe it was the EFI fuse)

If you got 12V over a fuse, its dead.
If you got 0V over a fuse, its live.

Dont know if that helps you out, but i have a problem figuring out where you are measuring...

[Ivan141]

probably between ground and each side of the fuse...

[Knudsen]

Ahh okay.. I usually measure over the fuse, but then; I work with industrial installations - not excactly the same

But car-wise, if theres 0V over a fuse, its live.

[Red]

"over a fuse"
In US English...that works but is, ah, mangled<G>. We use "over" to mean physically above the fuse. We'd say measuring the voltage "across" the fuse terminals, or "between" them. (I'm afraid to ask how the British would say it, we made the mistake of allowing them to retain the right to use a common language when we gained indepence of them.<G&gt

Which is also why the new plastic ATC fuses in cars (including these) have two small holes in the plastic, one above each end. With an ordinary multimeter you can stick the probe tips in the holes to check without removing the fuse. Don't ask me how long it took me to find that out, that is an intentional design.

There's no hard rule for what you "should" measure from the device side of a fuse when the fuse is blown. That will depend on the circuit, and while it would be zero for a simple device--it might not be zero in a more complex circuit, like they've used in cars. Still, 10V sounds wrong for the EFI main circuit unless something is shorting into it.

[Knudsen]

Red
Sorry i danishifyed the phrase "across the fuse terminals"...
Shit happens when Engrish isnt the first language, but atleast you knew what my intention was. Ill try not to soil your beautiful language anothertime.

[Red]

Knudsen, we have many natives here who speak "Ynglitch" much worse than you do. Now, if I were to try saying anything in Danish, that would be a truly bad thing.<G>