Aygo Ecu ground location ?

[Frankla]

Do the can bus wires only connect from the ECU to the MMT? 

[flash22]

it all comes into the  CAN termination module (part of the main fuse box) A38

there are only 3 likely culprits ABS, MMT ecu and the Yaw sensor, without an oscilloscope, you are not going to be able to look at the bus waveforms - everything so far is pointing at the MMT ecu with it unplugged you can talk to the ECU, you get readings of 60 and 120 ohms show it 2 end terminations are working inturn the circuit is physically intact

A Techstream clone and a laptop will give a much deeper level of access

 

edit. unplug the clutch actuator on the front of the gearbox and see if you can talk to the ecu

[Frankla]

Yeah I'm going to ring around on Monday to see about an oscilloscope, as for when the MMT has been unplugged along with the cam sensor and IMMO my scan tool only picks up error codes related to the gearbox no b2799 error code ect which I thought would have shown up, anyway I shall unplug clutch actuator on Monday see what happens, is the A38 plug the blue behind the instrument cluster. 

[Frankla]

Is this all I need for my laptop? 

[flash22]

yes a Mini VCI

My mistake, long day and too much sun, see if A38 is wired for the MMT if not it is direct to BA3 as it is a non VSC car

A38 is located just above the MMT ECU location

 

 

 

[Frankla]

Yeah mine is without VSC, thanks for the information Bob enjoy your weekend. 

[Frankla]

I've unplugged the clutch actuator but it came up no error codes on the scan tool but gearbox warning light was on 

[Frankla]

I'm getting hold of a oscilloscope tomorrow but never used one but my friend will show me how it works, where shall i connect it to on the Bus wires at the at the ECU? 

[Red_Corolla]

1 hour ago, Frankla said:

I'm getting hold of a oscilloscope tomorrow but never used one but my friend will show me how it works, where shall i connect it to on the Bus wires at the at the ECU? 

Connect it anywhere on the network that you can easily access. If it's the CAN bus you're wanting to see, connect one channel betwen CAN-H & earth, then a second channel from CAN-L to earth.

The scope just draws a graph of the voltage. They're a bit fiddy to set up because you need to scale the horizantal (time) and vertical (voltage) sides of the graph.

Here's some settings I've used before that should work as a starting point for looking at high speed CAN:

- Use CH1 for CAN-H and CH2 for CAN-L

- Vertical scale for both: 500mV/div (div means division or one segment of the graph)

- Horizontal scale for both: 5uS/div or 10 if you want to see a bit more data in less detail

- Horizontal offset -2v for CH1 and -3v for CH2 (positions the two waveforms top & bottom on the display)

- Set a trigger on CH1 at about 3v

IMG_0313.HEIC

[Frankla]

Thanks for the advice Red Corolla, I was going to purchase something similar to that if I couldn't borrow one, one thing I noticed today the immo box has marks on it (tampered) so I opened it up and looks like a component has been resoldered or replaced but the immo seems to be working fine as it has fuel and spark

[flash22]

It had the keys lost at some point that is the eeprom the encrypted IMMO codes are stored in, the soldering doesn't look good

you can pick up can high and low at the obd2 port

look at the waveform with and without the A28 plugged in

[Frankla]

Yeah the soldering doesn't look good, my obd2 port doesn't have can hi or can low see pics, should the waveform be the same or different when A28 unplugged? 

[flash22]

ah it's pre 09 so k-line only, no can-bus diag that may be an issue with your scan tool, Techstream may also have an issue

Can Bus can be picked up at A38 or MMT ecu

waveform should be nice and crisp you will soon know if the bus has any corruption on the waveform

 

The best budget scope I have used is a 2ch Picoscope and its something I would trust they start around the £110 mark - my first scope was an ex-MOD one that weighed 40-60kg, turn it on and wait 30 mins for the valves and tube to warm up

 

[Frankla]

Thanks for the advice Bob I'll let you know how I get on. 

[Frankla]

Can't get hold of the oscilloscope till next week now also I think it's a one channel handheld one, can I still test the can bus if its a single channel oscilloscope. 

[Frankla]

This is the oscilloscope I borrowed I took two videos one with A28 plugged in and one with A28 unplugged,seems the waveform is different when it's unplugged. 

[flash22]

a bit of noise on can low but is borderline may be a bit of corruption as well, pull the eps and abs fuses and retest

[Frankla]

Is that noise on the blue signal? If it is that's CanHi. There seems to be more of gap in the waveform when the MMT A28 was plugged in, the fuses at the instrument cluster for the eps and abs I'm still learning how to use the oscilloscope I'll retest it tomorrow, thanks bob 

Edited August 4 by Frankla

[flash22]

The gaps are just pauses between messages on the bus, each message is between 4 and 16 bits, you can have 600-1000 messages on the bus a minute

as i said the noise is borderline - can high pulls up from 2.5v base, can low pulls low from 2.5v voltage is marginal with A28 plugged in, it is not definitive, but I would be tempted to put another MMT ecu in the car

just as an example,
Can dump.txt

this is what the raw data looks like

 

Yes, it gets complex real fast

 

[Frankla]

Thanks for the information Bob, these MMT ECU's are very hard to get hold of none of the breaker yards in the north east have any there's 2 on fleebay for £200/£250, just want to make sure that the MMT is possibly faulty 

[flash22]

unplug the abs pump and see if it starts, do the same for the EPS module

[Frankla]

Cheers will do 

[Frankla]

Haven't managed to disconnect the ABS pump or the EPS yet I haven't been well, I shall try that next week, all so that fnirsi oscilloscope that I borrowed had the old firmware on it which had a bug checking can bus signals ect, now I've been looking at the owon hds272s on aliexpress for £140 just to check my own cars if any faults occur. 

[Frankla]

Hi there, been a couple of weeks since my last post, ok then I unplugged the ABS pump and the EPS still no start,  I've checked everything on this car I think, so I decided to remove the engine ECU and opened it up to check inside this what found corrosion on the circuit board I cleaned it up with electrical cleaner and looks like some of the circuit board is damaged, I've found a couple of ECU's with exactly the same part number but don't no how to program it to the immobiliser any advice please. 

[Frankla]

Going to try and repair these links on the ecu to see if it starts.