[treasure]

hey all.
02 accent with 70k on it the 1.6L

here is the problem, the car sat for two years and when getting her back to life it would start so i started testing everything i could find. here was i get
gets spark
power to the cam and crank sensor.
all fuses and relays are good.
found out the ecm was not grounding the engine control relay to turn on the pump and injectors so i added my own ground to the grey/orange wire and the pump turned and and it fired right up.?

so my question is what does the ecu look for to turn on this relay?

it was fine for a few days but now even with the relay grounded (activated) the car doesn't start . but let it sit and try again in ten mins and it will start every other time i come home from work and try....but i do still get power to the pump and injectors.??
the might be a electrical monster in this car but i don't know what else to check.

i have another accent same year so i switch the ecu and every relay i could find over from the run ing car and i still have this problem, also changed the cam and crank sensor, so im at a dead stop.

 

[Barnyspup]

Interesting question indeed.


I worked up a simplified diagram of what goes on (see below).

See if that helps.

Jim

 

[treasure]

interesting so maybe its just the ignition switch not sending the initial signal?

 

[Barnyspup]

I would use a voltmeter to at least test for 12V at the fuses shown in the diagram. Test from Ground to each of the fuse, to be certain.

 

[treasure]

i dont get power to ecu fuse number two

 

[treasure]

but i do get power to the fuel pump relay

 

[Barnyspup]

Nothing on either side of Fuse ECU2?

Is Fuse ECU1 live?

 

[treasure]

ill check when i get home but from what i remember there was no power to either side of 2. but ecu1 did have power

 

[Barnyspup]

Both fuses get power from the same point. OK. Await more checking...

 

[treasure]

ok update here. got home and she fired right up, as where this morning she did not. both with the engine control relay grounded and both times hearing the fuel pump turn on. with my ground attached to the relay i get power to all three ecu fuses but if i disconnect the make shift ground i have NO power to either side of #1 or #2 ecu but get power to three and nothing to the pump or injectors, naturally.

 

[Barnyspup]

Did you test for power at Pin #13 (Ignition switch Input)?
You could measure that at dash Fuse #5.

 

[treasure]

yes dash fuse 5 has power! so that means the switch is getting power correct? but it could not be sending power thru itself (being the switch) and onto the ECU which in turn sends power to the engine control relay. maybe a bad ignition switch ?

 

[Barnyspup]

No, the Ign Sw must be OK. If Fuse #5 has power, it can only have come from the Ign Sw. Turn the key Off and Fuse #5 should go dead.

The only other easy thing I can think of are the numerous Grounds for the ECU. Shown in pic below as G10 and G11. These are located behind the kick panel at the driver's left foot. There is one more behind there, G04, which is not for the ECU. Check that they are tightened and that there is no corrosion.

It's possible that the ECU expects signals from other sensors and that if they don't exist will fail to turn on. But I don't have any info on this and don't know where to look either.

You could do a pin-by-pin comparison between the ECU plug on your other car and this one and maybe spot something missing.

Jim

 

[treasure]

yes you were right changing the switch did nothing but it made me feel better lol i checked both the grounds i could find sanded and re-installed and still the problem occurs. i also check and redid all the grounds in the engine compartment i could find. grr this is getting frustrating. any thoughts?

 

[Barnyspup]

Posted below are the other sections of the ECM connections:
(Total 6 pages)

All the sensors plus the coils and injectors apply battery voltage to pins on the ECU. In addition, on an auto box, the TCM applies more signals to the ECU. Since you checked all the other 12V supply inputs and the Grounds, there must be one of those other inputs which the ECU expects to receive before turning ON.

Make up some probe which will permit testing at the ECU harness plug (plugged in) with Ignition switched On.
Check the Pin #'s on the diagrams and against the other car.

Jim

 

[treasure]

status update!!!! i started tearing into the wiring harness out of last resort and to my luck i found at least ten wires that were heavily corroded and melted together.one of which being from the engine control realy, also the g10 and g11 grounds and others going in to the ecu. cut all the bad ones out and re did them all and now she fires up every time!

so a hint for any others that have tried everything look way up the harness right before it goes thru the firewall(i assume thats how the water or what ever caused this got there) and make sure all your ground and other wires are not toast. a continuity text makes this go a lot faster!

thanks for all the help!!!

 

[Barnyspup]

Good job!

And thanks for the update.

Jim

 

[gavinbrent71]

Will climb into my accent's wiring to check the wires,I have been struggling with the same issue

 

[Red Raspberry]

The grounding is all done in the ECU. The ECU usually has to see the crank sensor and maybe the cam sensor signal before it turns on the ground.