 | Home > Puma (Tdci) > 2009 2.4 TDCi ECU not communicating |
 
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16947   
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First step, check that all the relays under the driver's seat are making a very good connection in their sockets. The symptoms you describe are commonly caused by a poor connection on the main relay. They must be really tight, they are often loose or slightly corroded. If need be bend the spade on the relay slightly to make the connection better.
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17th May 2024 11:51am |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6502 
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Check the standalone 15A fuse which is on the power feed to the ECU, and fuse 41 (5A) which is the ignition switch sense feed to the ECU.
Also swap over the 'main' relay under the seat box with another. The main relay is the one with 2x thick brown/light green, thick brown/orange and a thin blue/red.  1988 90 Td5 NAS soft top
2015 D90 XS SW |
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17th May 2024 12:00pm |
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| Landy addict Member Since: 03 Dec 2022 Location: Argyll Posts: 72 
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Thanks Blackwolf & Martin, I had checked all the relays & all are clean & tight but will check again tonight. as for the fuses they are all good as in none of them blowen, there is no alarm or original central locking as it was the very base model 90 van. I will also swap round the relays tonight & see if that does anything Keith |
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17th May 2024 4:25pm |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6502
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Have you checked the standalone 15A fuse in the fuse holder under the seat?
Click image to enlarge The one floating around bottom right in this photo 1988 90 Td5 NAS soft top
2015 D90 XS SW |
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17th May 2024 4:30pm |
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| Landy addict Member Since: 03 Dec 2022 Location: Argyll Posts: 72
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went out for a look just now the single fuse was hidden so hadn't checked before bad news the fuse is OK but when I test it there is no power with ignition on or off to either spade.
dash when turn ignition on
clean & tight relays
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17th May 2024 5:05pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19677
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I would not be surprised if this isn’t a ground fault, especially if it is faults on multiple circuits but fuses and connections seem in-tact.
You can then get voltage leakage through various circuits causing unusually faults, significant voltage drop in scenarios when impedance is high due to load. Water or moisture somewhere it should I be can also be a culprit, but I’d imagine you have checked most of these things. Definitely check the battery clamps are tight and the main ground points though, and that they aren’t loose. Merely a loose component will make impedance sky high under load, and then significant voltage drop. So it will appear there is power, but much lower than it should be. Make sure the alarm and immobiliser is synced and deactivated. Beyond that it maybe a sensor. You’ve replaced the CP Sensor. It might pay to clear the codes after recording them, disconnect battery leave it half an hour and then recommend to reset everything. You can do continuity checks as well as voltage checks as well. Check the connector on the rear of the IPAC (Instrument cluster) hasn’t come loose). Diesel$ Live$ Matter. ⛽️🛢️👨🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧 |
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17th May 2024 5:30pm |
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| Landy addict Member Since: 03 Dec 2022 Location: Argyll Posts: 72
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Thanks custom90 tried looking into some of the things you mentioned
Re-checked all the earth connections all have good tight clean connection Should not be any water or moisture as this is a full restoration & all wiring has been in inside very dry conditions for 18 months. Checked battery clamps again clean & tight It's a basic 90 van no alarm or central locking (not sure about immobiliser but just standard keys no fob) Cant clear codes as the ECU is not communicating with the reader It communicates with dash so connection is ok there Continuity checks seem ok & when checking voltage all have been just over 13V so far excluding the Orange & brown wire connected to the individual 15A fuse mentioned above by Martin (that has zero volts) what is that for. |
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17th May 2024 9:40pm |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6502
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I think you have the ECU not being powered at all, which is why it won't communicate, it's asleep!
The instrument cluster temperature at the top, battery light on and no other engine lights or RPM means the ECU CAN bus messages either aren't being sent (which I think is the case) or not getting through (not the case here). I assume you tried the fuse voltage check on the 15A fuse with ignition on? If so, the lack of voltage on the 15A fuse means the main relay isn't switching on, or its supply fuse has blown. The "main relay" is what powers up the ECU. The main relay is supplied by fuse 5 (30A) in the seatbox fusebox. The output of this goes to various places but the one of interest is the individual 15A fuse, then onto the 14 way connector pair on the left (UK passenger) side of the engine, then to the ECU (top plug). The main relay is switched on by a switched ground from the ECU, the ECU switches this when it receives ignition switched 12V via fuse 41 (5A) under the steering wheel. The other thing to check is the ECU grounds. These are 3x ring terminals on a stud (I think) on the bulkhead near the heater valve bracket, engine side. I'm assuming this is a fail to start following your rebuild, so there's not one specific thing that's been done recently to cause it? 1988 90 Td5 NAS soft top
2015 D90 XS SW |
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18th May 2024 8:57am |
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| Landy addict Member Since: 03 Dec 2022 Location: Argyll Posts: 72
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Hi Martin Thanks for advice
Yes ignition was on at the time all these large fuses had power Click image to enlarge 15A fuse still no power with ignition on Click image to enlarge 14 way connector looks clean Click image to enlarge fuse 41 (5A) has power Click image to enlarge the grounds look clean & seem to have good connection Click image to enlarge these 2x relays where warm when I was doing all the checks Click image to enlarge Click image to enlarge what relay is the main one you talk about above Click image to enlarge |
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20th May 2024 9:51pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19677
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In your 2nd picture take the fuse out and check it, and also check voltage from inside the holder.
Also check that larger blue maxi fuse to the rhs in that photo, I seem to remember that’s important but I can’t remember what it is for. Martin has more knowledge on this than me, be sure that you use a main ground point on the multimeter too as that’s important when testing for voltage. It looks like this is one of these fault finding exercises, a break, loose connection or ground issue. Ground or loose connection is most likely, but Relays can go, but it’s not as common. If that fuse has no power there and ignition on, then there’s an issue between that point and its supply. If you are using a good or battery ground and voltage elsewhere then it’s not a ground. I’d continuity check each fuse in-situ, if you find one which has a break there’s the fault that can be traced downstream on that circuit. You’ll need to set the Multimeter to read Ohms, the closer to zero the better or a beep if not then there is the faulty fuse. Presumably you may know this anyway, so apologies if you already do of course, but if not might be helpful. In my experience a loose ground eye, or alive connection is often culprit. Due to vibration and things like that, a screw on a captive fuse being loose, a fuse being loose in its holder. A crack in a fuse leg or fuse element partially blown but not fully. You could also possibly “inject” power to that circuit if you rig up a temporary fused supply to it and then see what happens, if that works it does but it still shows there is an existing fault. It’s possible a relay holder terminal has backed out the rear, so it might be worth checking they are present. Obviously with a missing terminal that’ll mean it won’t work. Diesel$ Live$ Matter. ⛽️🛢️👨🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧 |
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20th May 2024 10:11pm |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6502
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For the main relay look for the wire colours I mentioned in my post above.
1988 90 Td5 NAS soft top
2015 D90 XS SW |
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20th May 2024 11:04pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19677
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I would follow as Martin suggests.
Also be sure to check both legs of the fuses have power, or continuity check them in situ in parallel. If you only check one leg, if that’s the input it’ll show power, but if the fuse is blown the output will see no power. If you continuity check them, then you can ensure the fuse is intact and not blown. If anything is showing below expected voltage, then I’d suspect high impedance and that is things like corrosion of a terminal, or ground that is not as clean as it should be or loose, and that can cause that. You’ll need to trace the fault, and follow the suggestions Martin has made as a guide to help you along the way. It might just be the Relay needs replacing, the internal switch contacts might not be too good or the coil inside it has become weak or a bit of both. Diesel$ Live$ Matter. ⛽️🛢️👨🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧 |
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20th May 2024 11:29pm |
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| Landy addict Member Since: 03 Dec 2022 Location: Argyll Posts: 72
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thanks guys
 I will check out the main relay tomorrow.
Sorry Martin I should have read through it again & would have seen you already described the main relay. And no need for apologies custom90 I appreciate all the advice as I am definitely no electrician. When checking a fuse I normally always check both sides to be sure then if no power (like the 15A for ECU) I take the fuse out & use the meter to check that. If you look at photo below you can see that the meter is reading (now don't laugh if I get this wrong) Ohms as the meter auto detects (it is just a cheep one so not sure if it is any good) the reading was the same on both sides of the fuse when ignition was on I think it was also the same when ignition is off. Click image to enlarge Tomorrow I will check again this time making sure I have a good earth for the meter, will let you know how I get on. |
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21st May 2024 12:12am |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 300 
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Reading this thread and making a note or two as there is a lot of useful info for someone trying to fault find👍
I'm not sure if I've picked up correctly on your description of how you are using the meter..at the end you seem to be describing using the resistance or ohm scale for checking for power on a fuse... If you are using the resistance or continuity function you don't have the power on the circuit.. you do usually remove a component to check it's resistance... Leaving it in circuit can give odd readings and you would need a correct wiring dig to be sure what you were actually checking.. If you are looking for power on a circuit, you use the correct voltage scale.. In your case DC volts.. Likewise if checking the volt drop, you need the circuit on and current flowing.. Whether you use the earth, or any other part of the circuit the meter reads the difference in voltage across those two chosen points.. 👍 If I've misinderstood sorry for the above👍😂 |
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21st May 2024 7:05am |
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