Aygo Ecu ground location ?

[Mjolinor]

So, after all that, a month of trying, lots of reading and these posts I have finally got it sorted.

For the next guy that struggles:

This car has always had an occasional problem starting. Two years ago it was fixed by a garage when they stuck a crank sensor in. This gave 18 months of being OK.

About 6 months ago it did the same again. I replaced the crank sensor and it made no difference.

Much looking and I discovered a blown MOSFET in the immobiliser and replaced it. It made no difference, still no start.

Bought a complete ECU / lock / key set, still no start.

Now, having looked at every single image of crank sensor output I noticed that mine was higher than all of them. They seem to range from about 5.5 volts to 8.5 volts peak to peak. Mine was around 10 volts. I put the old sensor in and it worked with both my replacement ECU and the original ECU. I put the new sensor back in but packed it out slightly (about 2 mm) and it works.

So basically one original fault and a second fault introduced when I replaced the crank sensor. Two faults is always a dog to fix but boy do I know a lot about the wiring and electronics on these things now. 🙂

 

 

 

[flash22]

09 is a changeover year IIRC there was a change in sensor supplier, it was either an incorrect part or just poor quality Chinese junk some sensors do come with shims - A sensor too close to the reluctor will drive the amplitude/voltage high esp with a 2 wire sensor

I find it useful to bounce ideas around, it gives you a different perspective, very few garages will perform proper diagnostics these days, let alone use a scope, It's just aiming the parts cannon and fire

 

 

[Mjolinor]

Such joy. This morning it will not start, just whirs over as it has done for months.

 

Yesterday I used it all day, stopping and starting no problem hot or cold.

[flash22]

cranks over or just the starter motor spins, give the solenoid some percussive maintenance

[Mjolinor]

Cranks over fine.

Interestingly I cannot get into the ECU over OBD. It gets into the rest of the car OK, restraints, immobiliser, etc.

Just swapping the ECU set out again, see if that sorts it.

 

I really do wish I had not put the dash back in yesterday. 🙂

[Mjolinor]

ECU set changed, still no go.

No fault codes. If I unplug crank sensor I get a fault code so wiring is OK to that unless one of the legs has a short to earth or B+, I have tested for both of those.

 

[flash22]

Check the pin fitment on the crank and cam plugs, repeatedly disconnecting them the terminals can lose tension

[Mjolinor]

It logs a fault if they are not connected. I already checked that.

 

The inability to get into the ECU over OBD makes me think maybe the ECU end plugs may be intermittent.

They are only guaranteed for about ten insert and remove actions are that type of plug.

[Mjolinor]

Well there you go.

Crank sensor resistance 300k rather than 1700 ohms as it was yesterday.

 

[Mjolinor]

Intermittent solder joint in CPS.

Put it back in after soldering it and it works fine with the new ECU set.

Put the original ECU set back in and no go + no OBD possible.

Back to replacement ECU set and all good.

So, conclusion:

Faulty (intermittent) crank sensor

Faulty new replacement crank sensor

Faulty MOSFET in original immobiliser

Something else sometimes up the spout in the original ECU

I am now quite confident that it will be sorted when I get another new crank sensor and I am going to get an original one if someone will tell me what it should be, Valeo I assume, possibly Bosch. I have had it with FAI and other cheap crap.

This is not the week to buy a lottery ticket. With my luck my house would burn down.

 

[flash22]

MK1 uses Valeo, mk2 uses Bosch

Can you drop me a PM with your VIN, I can look up the sensor, as above 2009 there was a change in parts

[Mjolinor]

Hmm, I thought it had Denso originally.

No need for secrecy, it doesn't do anyone any good. 🙂

JTDJG18C80N391728

The Internet reckons no change from 05 to 12 as far as I can tell.

[flash22]

Built - 07/2009

Model - KGB10R-AGMRKW 

it's 3 door as well

 

2 Types from 12/2008

90919-05062 (Denso oem one will be marked 029600-xxxx)

90919-W5002 (Valeo)

both numbers cross on the aftermarket

[Mjolinor]

Cheers, much appreciated.

 

Been using it a couple of days and it seems fine with the repaired sensor.

I will fit a new one as this one has no protective can on and it could fall apart into the engine the consequences of which could be dire.

 

[Frankla]

Hi people, my peugeot 107 auto 2008 cranks but no start I'm getting DTC B2799 immobiliser fault; Engine immobiliser system malfunction Status: Confirmed. I've checked all wiring from immo pins 12 and 13 to ecu pins 6 and 33 seems all good could it be faulty immobiliser unit and my fuel pump primes when ignition is turned on and when I crank the car, would camshaft and crankshaft sensors show up on DTC if they were faulty.

[flash22]

Tried a spare key ? as on page 3, check the ground point at the front right of the cylinder head as you look at the engine

losing the ground to the coils makes the ECU think it is immobilised

[Frankla]

Thanks for your reply, I've tried the spare key also tried bridging the diagnostic for 35 mins and checked the 2 wires on the cylinder head they still attached,does the immobiliser cut the fuel pump out? 

[Frankla]

Hi there, I've checked the immobiliser for earth and power supply, now the immobiliser is supposed to have 3 power supply on the pin 1 green pin 2 black pin 3 grey but they is no power at pin 3 grey so put a 12v supply to the grey wire and the car starts, can any tell me were the grey goes or will it be OK just to permanently put a 12v supply to it. 

[flash22]

Grey is ACC (12v accessory switch live) check the fuse on the side of the cluster if not, put the key ignition, and push up as you turn the key - from there if you have no luck you need to look at the ACC circuit

if the immobiliser does not see the correct voltage signals it will throw a fault

[Frankla]

Thanks for getting back, do you think it'll be OK to put a new acc feed to the grey wire with a fuse if I can't find the problem, the fuse on the side of the cluster is OK. 

[flash22]

is the ACC fuse getting power?

[Frankla]

All sorted now, 15 amp fuse at (13) next speedo when I was putting my test light it was showing power either side, but I went back to double check I had my other test light on the grey immo wire and when I checked the fuse again the grey wire became live I gave the fuse a wiggle and test light on the grey wire was flashing on and off also fuse blade was slightly dark so bad connection on the fuse holder. Thanks for your help 

[flash22]

Glad you got it sorted, i would clean it with some contact cleaner to make sure it's clean

[Frankla]

Yeah I've cleaned it with contact cleaner and I modified my wife's nail file to to fit in the fuse holder to make a clean contact 😂😂