207 Non start with non ECU communication

[cdjmartin]

Hi,

This is my first post on the forum so hello to all and go easy on me!

I have a 2008 207 with some frustrating electrical issues, the car suddenly, with no previous symptoms, failed to start whilst also showing the standard anti pollution fault, the engine won't crank. Upon diagnostics the ECU can not be found so I can't read any logged faults. I have previously successfully used my diagnostics kit with this car so I know the kit works. I can connect to instrument pack.

I have read that broken wires have caused this type of issue and I have started to unwrap harnesses in a desperate search but nothing so far. I have also changed the fuse box as I have had non starting issues with this car before and it was a failed fuse box. There is zero signs of corrosion on the ECU plugs.

Something that I have noticed as odd is that on fuse F10 and F5 (I believe they are powered by the same relay in the fuse box) there is a unusual voltage, which with all sensors connected and ignition on is around 3-4volts, this seems odd, surely it should be 12v or 5v and I would expect 12V. I am thinking that something is pulling this voltage down, maybe a failed sensor shorting out. I have tried disconnecting all the sensors I can think of, including ABS and all the other fuses one by one, and the voltage never goes up to 12v, it did go up to 6 at one point with various items disconnected.

Another detail is that with fuse F10 pull out, I get voltage on both sides again at around 3-5 volts.

I have spent a lot of time checking all of the earth straps and disconnecting sensors with no success and I am beginning to run out of options.

My head is telling me that this odd voltage on Fuse F10 is related to the failure to start and ECU comms. If someone has a similar car I could be very grateful if you could check the voltage between ground and both sides of fuse F10 with ignition on. The fuse box is a L11 type.

I also get some odd readings when I check the resistance between ECU earth and battery -ve, with ignition off and doors closed this is very low as you would expect, less than 1 Ohm, but with ignition on it raises to 15 Ohm, I don't get this at all, could this also be linked to a faulty sensor that is shorting to ground?

I get a 12v going in to the ECU on the plug closest to the bulk head on pin C3 I believe this to be correct.

Long post, sorry about that.

Chris.

[Hell Razor5543]

Hi, and to the forum. While I will not be able to help you, I feel that you have given enough information to help others who know Peugeots.

If you cam post up the vehicle VIN it could help. For security reasons it will be obscured so only Forum staff can read it (I am not Forum staff). The following is an example;

VF7**************[VIN obfuscated, can be read by forum staff]

[dfabrici]

Hi, what engine are we talking about? So to start thinking about finding diagrams. First of all you should check power lines to the ECU, F5 and 10 should be powering ecu actuators and fuel pump, but it strongly depends if we're talking diesel or petrol. However, if the ECU is correctly and completely powered, you should take a look at CAN lines resistance and activity, but the latter requires the use of a scope. The relay inside the BSM that feeds may be powered by the ecu itself, and it might be not latching until cranking of the engine (but I'm just supposing). To make our forum admins be able to find the correct diagram for you you should post the VIN number (it gets automatically shadowed, visible only to the admins).

Bye
Davide

[cdjmartin]

Thanks for the replies, the VIN number is as follows

VF3**************[VIN obfuscated, can be read by forum staff] and it is a diesel.

It maybe a red herring but today I am going to concentrate on this low voltage on fuse F10 and F5, I'm going to unplug everything I can find to see if I can get it up to 12v as my gut feeling is that is being pulled down by something, I'm also getting slightly odd earthing issues as well which could well be linked.

Whist I haven't yet checked the continuity of the CAN lines I am reasonably sure that they are ok as I can get vehicle data from my diagnostic equipment it just won't connect to the ECU.

If I disconnect all of the multi pin connecters from the fuse box I get zero volts on both sides of fuse F10 with ignition on, as soon as I connect the grey connector (far right) I can hear a relay latching and I get the low voltage on F10, so I am confident the relay is latching. But today I will explore this more.

Thanks
Chris.

[GiveMeABreak]

Hi Chris and welcome to the Forum.

So you have the 1.6 HDi 92 DV6ATED4 engine.

I'll stick the Starter / Alternator / Pre-Heating Diagram up followed by the Injection Diagram to get you going. Davide might be able to assist, as I have a Windscreen replacement for the Aircross to supervise any time now

Most of the codes are on the Wiki here:

Wiki Electrical Component Codes

Starter / Alternator / Pre-Heating





Injection

[cdjmartin]

Hi Marc, thanks for the wiring info. I have to admit I'm not much of an electrical engineer so my experience with these diagrams is limited. I'm looking at F10 and it runs to:-

1233 - turbocharger pressure regulation solenoid valve.
1267 - diesel heater

Should these both be my next starting point?

On the ECU which plugs are CMI, CH and CME? I assume CMI is the larger plug but which is which of the two smaller plugs?

Thanks
Chris.

[cdjmartin]

Another quick point, I cant get any of the cable numbers in the injection diagram above to match, am I miss reading something?

[cdjmartin]

OK, so last quick point before chill and wait for replies!

I don't think I have a diesel heater and more to the point I think I read the wiring diagram wrong. So I concentrated on the turbo solenoid, when I disconnect this I long longer get a low voltage on both sides of F10, which by looking at the wiring diagram makes sense. But the low voltage is still there on the hot side of the fuse. Is this a red herring or a symptom of the real fault.

Another find is that I have 2 volts between the chassis of the ECU and ground. This seems weird - ECU failure? Could this be the root cause of everything.

Thanks
Chris.

[dfabrici]

Hi, I'm nothing near an expert, but I'll do my best to help. So, first of all: F5, is it even populated on our PSF/BSM? It seems to me that in your case it shouldn't even be there, although I might be wrong. F10 feeds only the solenoid of the turbo regulator, the diesel heater is fed by R3 and F14.

As for the ECU power supply, you should at least have another 12v fed by the BSM at pin M2 of the 48 way brown plug in the ECU, fed by F1 (check for integrity) on the BSM, which is actually the main power source for the ECU. If you don't have any access to the ecu via diagnostics, I'd say the ecu is off, since the dialogue from the obd port is not via CAN shared with the other modules but via K-line directly to the ECU, but I could be wrong nonetheless. F10 is directly supplied by R2. If you have low voltage on the hot side with the fuse(s, if F5 is fitted) removed, there's probably something wrong with R2 or, again, R1, which is the relay feeding the coil of R2 (it's like a chain reaction: R1 gives voltage to the coil of R2 which in turn gives voltage to the coil of R3. The latching are ground-driven by the electronics inside the bsm.
At least that's how I got it looking at the diagrams.

Indeed the 2v between ECU and ground are strange, even if I wouldn't care too much, given that the ground terminals are shorted directly to the ground. This is the reference that the internal circuit uses as ground. Check pins G4 and H4 in the 32 way black plug for direct short to ground.
I didn't get what happened to the voltage when you disconnected the solenoid.

Last but not least, plug naming . Don't concentrate on CMI CME CH... You have to read the bold abbreviation next to the connector, like 32V JA. xxV means xx voies (which is french for xx-way), so in this case 32V means it's a 32-way connector. Beware that it does NOT mean there's 32 wires actually connected, but it's the maximum number of wires the plug can accommodate, since different vehicles may or may not have some wires fitted. the other two letters indicate the colour of the plug, in this case JA means Jaune (Yellow in French). So 32V JA means a 32-way yellow plug.

Oh, and what do you mean with "I can't get the wires numbers to match"?

[GiveMeABreak]

The actual wiring codes are not shown on the Wiki - only the 'Hardware' Components. I just wanted to post these as I've been offline most of the day dealing with my windscreen replacement.

[cdjmartin]

Hi Gents,

Thanks for the replies, I'll try and respond in order and as clearly as I can.

I agree that Fuse 5 is not be relevant here, it does have a fuse in but I do think I need to consider it. From the wiring diagram posted above it does seem that Fuse 10 supplies only the turbo solenoid, unless there is another circuit diagram that also features F10 - Is this possible?

I can confirm that I have multiple 12v going in to the ECU, I can't remember there is on pin M2 of the 48 plug - I will check this tomorrow and also check it back to Fuse F1

Black plug G4 and H4 go straight to ground.

I agree that F10 should be powered by the two relays within the fuse box. I can see that thinking there is a fault with either of these two relays is a possibility, but I have two fuse boxes, the original and a replacement, supposedly from a working vehicle. Having exactly the same fault on both seems unlikely although not impossible. On the flip side how, if these relays are working fine how else could the voltage be pulled down, and also why would it be causing this fault if it only feeds the turbo solenoid.

Another troubler is that with the turbo solenoid connected I get a voltage of both sides of F10 when the fuse is removed, this voltage disappears when the solenoid is unplugged. I just don't get this. If the turbo solenoid is the only component wired to this fuse then the voltage must be coming from the ECU. Due to this I have ordered an identical second hand ECU again from a working car.

Thanks for the clarification on the plug labelling, I did manage to work this out, well, I say worked out, I actually just read the info in the wiki, which I have to say is extremely useful.

Regarding the wiring I thought that the numbers on the wires in the diagram would match the numbers on the actual cables, clearly not!

All my activity is focused on this odd voltage on both sides on F10, but it could be a massive red herring, I'll also spend some more time stripping harnesses tomorrow in the search for a broken wire.

Thanks again
Chris.

[dfabrici]

Hmmm... well first of all what is F5 on your car? It should be written in the user manual. I'm quite sure it shouldn't be anything there, F5 is used for voltage supply to the fuel pump (petrol) or turbo actuators, but only in the 1.6 thp engine. F10 in your case is only used for the turbo pressure solenoid (the one on the underside of the engine, towards the back). If both the BSMs are showing the same behaviour then I'd search elsewhere. Here's the part of our interest of the BSM (it should be for the most part correct for your vehicle)

I'd remove F10 and F5, measure the voltage, ignition off, present on both sides of F1. Should read 12V as directly connected to battery. Then I'd turn the ignition on and measure voltage at pin 5 of the 28 way black plug on the bsm, again, must be 12v, as it's the main supply for the engine ecu, MAF, HP pump solenoid, engine air preheating... Subsequently, you should check voltage at the hot side of F10, which is the dreaded one. The fact that with the fuse disconnected you find the same voltage on both sides of the fuse actually doesn't surprise me much: the actuator is actually a solenoid (a coil of wire), thus when the fuse is disconnected probably the ECU latches internally the other side of the solenoid to the supply itself, since otherwise it would be floating above ground, while this way the ecu is sure the solenoid gets absolutely no voltage in any case across its poles, but I may be completely out of track. If you notice, from the diagram, once you disconnect F10 and 5 to cut out everything downwards, the voltage on the hot side is derived solely from the battery itself via R2. Unfortunately it's very difficult to see what happens to R2 as, on one side of the coil the voltage is the same as the one measured on pin 5 before, on the other the actuation is driven by the electronics themselves.

[cdjmartin]

Hi dfabrici,

Thanks for the reply, you've added some good things to check, I'm going to take a day off looking at the car today but will get back on it tomorrow. Would it be possible to share the wiring for the complete fuse box, as I would like to understand the full picture.

Thanks
Chris.

[dfabrici]

Hi, sure enough, no problems!
This one SHOULD be the one for your BSM, they're not too much different if speaking about the same engine. Should this be wrong, probably Marc will be able to help with the correct one.

Will wait to know what happens.

Bye
Davide

[cdjmartin]

Morning,

So, latest findings which are at least new if not conclusive. The fuse box wiring diagram has been really useful, I have found that the output voltage of relay 1 (pin 5 of the black 28 plug on the bsm) is only 1.9V rather than the 12V it should be, this in turn is likely why the voltage output of relay 2 is low which is the same low voltage on fuse F10.

This 1.9V from pin 5 goes to pin M2 of the brown 48 ECU plug so the ECU is not getting enough power. So my focus is now on why the voltage output of relay 2 is low.

I have 12 volts on fuse F1 which feeds relay 1, the other connection is pin 9 of the black 28. If I manually ground this pin I can hear relays clicking and I get 12V on Pin 5, as it should be according to the wiring diagram. Pin 9 is a grey cable that I can trace back to pin E1 on the brown ECU plug.

So, I'm jumping to conclusions but it would appear that the ECU is not grounding this grey cable appropriately, so the next question is why, faulty ECU? I have ordered a replacement, second hand with identical part numbers Will this need coding?

Still have the weird 2-3volts on the ECU box.

I hope that all makes sense!