Newbie - Immobiliser Help??? Please

[ward84]

Hello I am having problems with my 172 I cant get the immobiliser light to go off when I turn the ignition? Please can someone help, many thanks.

 

[MicKPM]

Any other lights on or just the red STOP and oil light?

 

[TM.]

Any other lights on or just the red STOP and oil light?

& can you get the engine to turn over? If so does it stop after a couple of seconds or keep going till you stop turning the key?

 

[ward84]

The engine does turnover but it just will not start I cant hear the fuel pump prime, the immobiliser light is on constantly as soon as the key is turned and when I do this all I can hear is a click from the left side, glove box area? Sorry it only turns over for a few seconds then stops, I have to turn it all the way back to position one to attempt to turn it over again.

 

[ward84]

I have already checked crank sensor just in case. Checked relays and fuses cleaned battery connections and recharged it. Also tried the key in position two whilst disconnecting the battery for five mins but it still stays on solid? But if it helps I did try to reset the ECU by disconnecting the battery for a few hours previous to this problem so this seems to have caused it.....:S

 

[TM.]

OK, it does sound more like an immobiliser problem than anything else, there's a few ways to reset the ECU to try and get it to sort the immobiliser out, one method I know of is to turn the key to position two and disconnect the battery for a few minutes.

 

[ward84]

Tried that a few times and had no luck, any other ideas mate? But I was not to sure if you had try to start it after doing that or to lock it walk away for 30 mins and come back and try to crank it?

 

[MicKPM]

Is the electrical connection fault light on (ignore the diesel pre-heat light)?

This warning LED always being on can happen for a number of reasons such as when there is a CanBUS or general connection fault and doesn't specifically mean the imob itself is at fault. CLIP diagnostic required to see whats occuring and go from there. Noramlly though its silly things that make this happen but you need to know what you're looking for.

Mick

 

[ward84]

Cheers. Yes mate its exactly as in that pic but also with the round LED lit constantly. The problem started when I tried to fix a different fault which was failing tail light even after I changed the bulb, so then I checked and fiddled with wiring every where including under the glove box where the UCH is, which I think is where I might have pulled a wire loose or even wiped the ECU or something where I removed the battery. My personal theory is its the key and UCH and immobiliser not in sync or theirs a loose wire that was disrupted when I was fiddling around under the glove box. I've tried everything else even moving all the wires I might have disrupted but still with no result. Its got to be one of these hasnt it?

 

[MicKPM]

You won't "wipe" the UCH or ECM without CLIP or something else that can program so don't worry about that chap. The units are normally bomb proof unless you give them a bloody good bash, circuit short or get them wet. What the vehicle is telling you by means of the LED being on is that the key has been detected and code registered/accepted but the imob system is still armed as there is a Level 1 fault on a vital system so the running of the vehicle is not authorised. This rules out a fault with the key, decoder ring, wiring and UCH on the Imob system IMO.

Firstly, and as you've been playing, have you checked all the fuses are intact? If so and they are then its proberbly a CanBUS connection fault due to poor power/earth to one of the systems that you've disturbed and/or not reconnected properly. Whilst its not a bad thing its not exactly great either as there are so many individual systems all linked by a "twisted pair" of wires that you'll never know where to start (unless there's an obvious, visible fault) without running some kind of network conformity check... by this I don't mean plugging it in to a generic code reader to see what 'error codes' are shown (although this wouldn't be a bad place to start but if it says something like "No communication with ABS module" for example DON'T let anyone replace the component without first confirming the network and wiring infastructure is 100% sound or else you'll most likely spend a wedge and still not fix the problem). My honest advice would be take it to a workshop that is CLIP equiped OR to somewhere that is armed with a decent 2-4 channel scope and qualified to use it!

Jays '182 that came in on Saturday had a similar problem which he'd pulled to pieces himself trying to fix (and actually did a pretty good job to before admitting defeat). He checked for continuity on all the important lines plus all the power and earths which all showed good results - I to checked these feeds on my digital multimeter and confirmed the power showed a good +12.3v to +12.8v yet this slight change in voltage set some alarm bells ringing. I checked the Can signals and finally the power with the scope which showed the same wire as having +3v to +12.8v @ 10ms which is an obvious problem as the ECM was always switching itself on/off due to unstable power supply. One new wire later and it starts like there was never anything wrong.

The way CanBUS works is simple but not logical to *everyone* including those in the trade believe it or not... like automatic gearboxes, its black magic to them so if you do need help and are willing to pay for it be sure you choose who carefully as you can find yourself paying out a lot for someone to guess and use Google rather than actually fix your car.

So to recap... check the basics first; Fuses, Power supply, Earth conditions and most importantly check for obvious faults at multiplug joints like wires not entirely seated like the other (sticking out a bit) or even bent pins inside the sealed connection unit.

Mick

 

[ward84]

Cheers Mick, do you think its worth paying an auto locksmith to take a look at the key and immobiliser after all? I have looked at the fuses on the passenger side in the end of the dash but that's the only ones I've spotted apart from the relays by the battery. I have noticed a metal control box under the ash tray? What is CLIP and a CanBUS connection??? I've only noticed a couple of earth connections in the engine bay and under the back bumper. I've checked a fair few of the plugs and connections under the dash but others seem to be unreachable especially around the UCH. Is their any manuals for the 172?

 

[ward84]

Sorry about all the questions pal, I only know the basics when it comes to cars! :banghead:

 

[MicKPM]

No, I don't think a locksmith will be able to help with this as the key is being recognised and accepted but as there is a basic but serious fault (Level 1) the vehicle is not authorised to start.

"CLIP" = Renaults dealer level diagnostic

"CANBus" = An automotive specifc (but not exclussive) "network" infastructure developed by Bosch, which is pretty much standard throughout all vehicles made since 2002. CAN is a serial bus protocol used to connect individual systems and sensors as an alternative to conventional multi-wire looms which in short makes wiring looms cheaper to produce, lighter in weight and easier to route. It allows numerous computer controlled systems to communicate at once down single wire or multiwire networks.

I've got to be honest and say its most likely going to be something you are going to need help with. A mobile auto-electrician will be a good place to start matey.

Mick

 

[Mike@Rentech]

Broken multiplex wire in engine bay, it corrodes at the point the main loom turns 90 degrees to goto ecu.
White or grey wire , they are twisted round each other.

 

[ward84]

Broken multiplex wire in engine bay, it corrodes at the point the main loom turns 90 degrees to goto ecu.
White or grey wire , they are twisted round each other.

You got any pictures of it or its location pal, already had the ECU pulled out and didnt see anything like that??? Cheers

 

[ward84]

Cheers again mate, how much will an auto electrician cost roughly and does anyone know any local to me as I phoned the only three mobile auto electricians I could find in my area and not one carries diagnostic equipment.....???

 

[MicKPM]

Some auto-electrician then! Costs vary greatly from £40 to £65 an hour.

Mike is telling you to inspect the loom from the ECM all the way back to the R67 connection in the engine bay fuse box for breaks. Just be wary though as there are two "twisted pairs" in the loom and they're not always white/grey as Renault like to change loom specs and they can be white/purple or even white/orange.

To get at any of this you will have to strip off the plastic outer protection and the tape cover also - enjoy and welcome to my world.

Mick

 

[ward84]

Cheers for the help everybody, its been sorted now. Cleaned it the other day and pulled out a few fuses then played with the positive wire on the battery think it was touching the bodywork..... Started first time every time. Thanks again

 

[Quid]

Mick help me pleeeease.

I have this same problem, which fuse is for the UCH?
And where aboutr are the connections that I need to check.


Many thanks
Antony

 

[MicKPM]

Check the fuse box in the passenger side of the dash... The legend will show you which fuse is for the UCH. The wires you need to check vary depending on the actual fault so re-read what Mike wrote earlier in the thread and go from there.

Mick