ECU Code 45 - Charge Control Solenoid

[ianelvar]

Yup, you can pull it through into the bay without too much trouble, and a bit or ranting about what an annoying place the ABS unit is in :Giggle

It should all amount to the same thing with grounding. The case is attached to the chassis which is attached to the battery -Ve. It might attached through the loom to the engine as well, but this is also attached to the chassis, and the to the battery -Ve, so we end up with the same thing. Or that\'s the theory anyway....

I\'m happy to talk to you on the phone if you think it might help. I\'ll PM you my number if you want

[imebgo]

Cheers!, If you want PM me your number I can phone you this evening when im front of the car and I can go through whats going on

Cheers,

James

[ianelvar]

Can\'t PM you for some reason, so get me on 01256 881114

[imebgo]

Ok, cheers,

I had a look around tonight before it started really bucketing it down.  Else I would have given you a ring!

I have pulled the wiring through the firewall to test and inspect the wiring easier than breaking my neck down in the footwell.

I measured some resistance:

ECU Charge Control Solenoid Pin to -Ve with everything connected: 30 ohms If the circuit was broken should the resistance be much much higher?

Ground Pins on ECU Terminal to -Ve 4ohms (sounds a bit high for what essentially is a length of copper cable?)

Please tell me im heading in the right direction lol!

James

[ianelvar]

I take it that was with ignition on?

the 4 Ohms sounds just about acceptable, but it might well be worth adding some extra grounding just to be sure.

30 Ohms sounds a bit on the high side though. I don\'t actually know what resistance the solenoid coils are, but it won\'t be high.

Can you measure one without anything else connected?

If I\'m right in assuming that the coils are around 50 Ohms, then having 30 Ohms in series with it in the circuit might well cause problems, as only slightly more than half the voltage would be dropped over the solenoid - the rest being dropped over the ECU before finally getting down to -Ve

The problem would be even worse if they\'re lower than 50!

Can you measure a few sols on their own and let me know what their resistance is?

Do you get the same resistance to -Ve for ECU pins that actuate other sols?

Would be good to have a reading for the double throttle, which should be active, and something that should be inactive.

You\'re definately headed the right way now!

[imebgo]

I think im missing something here, the 30ohms i measured was from the pin in the ecu to ground, how could that reflect the resitance of the solenoid coils?  I am measuring after the solenoid, does this take into account the resitance of the enitre circuit?

To clear things up do you want me to measure resitance over the working solenoid terminals when connected?

James

[imebgo]

"If I\'m right in assuming that the coils are around 50 Ohms, then having 30 Ohms in series with it in the circuit might well cause problems, as only slightly more than half the voltage would be dropped over the solenoid - the rest being dropped over the ECU before finally getting down to -Ve"

There is not voltage drop over the solenoid?  Im mis understanding again!

are you saying that the total resitance of the circuit is 80ohms so it must drop 12v over the 80ohms which must mean that over the solenoid (50ohms) it must drop a proportionate amount of 7.5v?  How does that reflect the 12v at both terminals?  LOL  I wished I payed attention in physics!

I may have to phone you tonight if its good weather!

Thanks.

James

[ianelvar]

"If I\'m right in assuming that the coils are around 50 Ohms, then having 30 Ohms in series with it in the circuit might well cause problems, as only slightly more than half the voltage would be dropped over the solenoid - the rest being dropped over the ECU before finally getting down to -Ve"

There is not voltage drop over the solenoid?  Im mis understanding again!

are you saying that the total resitance of the circuit is 80ohms so it must drop 12v over the 80ohms which must mean that over the solenoid (50ohms) it must drop a proportionate amount of 7.5v?  How does that reflect the 12v at both terminals?  LOL  I wished I payed attention in physics!

I may have to phone you tonight if its good weather!

Thanks.

James

Got it in one! For the pin ON state, I\'d expect resistance to be much nearer 0 Ohms. For the OFF state I\'d expect it to be 1000\'s of Ohms, if not 1000000\'s of Ohms.

You might remember from school an experiment which involved putting a light bulb in a circuit with a switch and a battery, and connecting a volt meter and an ampmeter in the circuit so you could see what was going on? Then putting another bulb in in series with the first, and observing that they both glow, but much dimmer than just the single one. This is because each bulb only has 12/2 (we now have two resistive elements in the circuit) volts dropped over it.

This is exactly the same circuit, except the switch is the ECU and the solenoid is the bulb. What you\'ve found it that there is a resistance through the switch, so we can think of the circuit as being a switch, a resistor, and a bulb all in series. The switch should have about as much resistance as a piece of wire - almost nothing for our purposes, but your reading suggests otherwise. Whilst it\'s not a mechanical switch in the ECU - it will actually be a transistor - it should show very low resistance when it\'s in its ON state, and letting current flow through it.

If you\'re still a little confused, wikipedia probably has some good info about circuits, and will probably explain things much better than me!
It\'s one of those bits of knowledge that if you dont use often you\'ll probably never remember. I only retain it because I do a lot of stuff with electronics, and it still confuses me sometimes.

I should be in this evening, so feel free to give me a call.

[imebgo]

OK, Im with you on all this.

But what does this point the problem too?  We know there is too much resitance over the ECU which is casuing the circuit to not draw enough current to do the work for the solenoid? right?

So, the ECU is screwy, or the ground is bad?

J

[imebgo]

Swapped the ECU for one out of mine and the charge control solenoid works!

LOL!!!

All that for an ECU Swap :flamed

Thanks for your help, I have learnt a lot about the electrics of the car and hopefully should have it on the road again soon.

James

[ianelvar]

Dude, that\'s really cool you got it fixed. :Thumbs-up  Glad I managed to be of some help.