172 Cup Limp Mode - Throttle pedal issue?

[brucie286]

My 172 Cup (2003 / 63k) has been going into limp mode for the last few weeks. It happens sporadically and clears when you turn engine off then on again.

Sometimes it will do it twice in a row, but then it may go for 3-4 days with no issues. Sometimes the engine management light comes on, will stay on when the limp mode light has gone out and drives fine again.

I took it to my local garage who have done various bits on it for me and they diagnosed a throttle pedal potentiometer fault from the OBD check. I had the pedal unit replaced yesterday, they tested it all afternoon with no issue. I collected it and less than two minutes from the garage it went into limp mode again.

Has anyone had this fault before?

Anyone got an ideas on what to check?

Thanks (disgruntled Cliosport newbie)

 

[l33th3tr33]

Try cleaning up the connections to the throttle body, that's what sorted mine.

 

[MicKPM]

Extremely unlikely to be the TB on a Cup tbh. More likely a signal incoherence issue

 

[brucie286]

Thanks for the info. I'll give it a go tomorrow.

Shall I just use WD40 on the connections?

 

[l33th3tr33]

Extremely unlikely to be the TB on a Cup tbh. More likely a signal incoherence issue

Sorry I'm too tired!

I meant the throttle pedal. And regarding cleaning then up, I just clipped and unclipped the connection a few times, not had it since. (Touch wood)

 

[brucie286]

Sorry, i delayed my response and commented on TB cleaning.

I had a new pedal that fitted yesterday. Shall I clean the connection to that and the TB?

 

[l33th3tr33]

Sorry, i delayed my response and commented on TB cleaning.

I had a new pedal that fitted yesterday. Shall I clean the connection to that and the TB?

Just the connection to the pedal. I never touched the TB.

Actually from memory, you can replace the wiring to the pedal itself, I think that fixed it for someone.

 

[MicKPM]

Squiggly line orange light on?
Vehicle revs to 2.5-3k?

Press and hold the brake pedal then, with the brake pedal still pressed, does it start and rev okay/light go out until you release the brake pedal?

 

[brucie286]

i had a new pedal fitted yesterday and its made no difference as the fault is exactly the same.

Yep, squiggly line and not revvign above 2.8k ish. What would the brake pedal thing prove/disprove?

 

[MicKPM]

So you're swapping bits without any testing and its not working... classic fail.

Do you understand how these cars are wired and how specifically the 172 Cup throttle potentiometer circuit works? If not stop asking questions and just start the car with the brake pedal pressed (keep it pressed down after it starts to) and tell me if it starts working again... I'm trying to actually help you here.

Mick

 

[brucie286]

OK mate. Steady on. I'm only looking for advice; not an argument!

Thanks for the info. I'll try the brake pedal exercise and report back.

 

[MicKPM]

LoL I wasn't bring mardy just not willing to explain what I'm doing... now go do it!

 

[brucie286]

OK, no worries.

Just been out to the car and it didn't do it on a 20 minute drive. Only got the engine management light on at the min. It always resets itself and the limp mode light goes out every time I turn off and on again.

Hmm...

 

[MicKPM]

In that case then you're going to need to get it checked for codes but I'll bet £20 with you that it comes down to an inconsistency between pedal tracks 1 and 2.

Personally I'd want to data log the two tracks at both the pedal and ecu to see whats occurring as it is either a wiring or ecu fault in my mind at the minute.

 

[lemonnobby]

Could be the big white connector in the fuse box.
mick why were you saying about the brake pedal for..

 

[MicKPM]

Because there is a little known issue specifically with the Cups and the 5v reference voltage which occurs with a dash loom fault.

Its a throw back between the brake pedal switch and the "brake on" signal to the ecu which seems to f**k up track 2. When you scope the two tracks you can see it obvioisly causing a difference between the two track signals which the ECU interprets as a pedal fault when in fact its bugger all to with the pedal and depressing the brake pedal fixes it.

 

[Djw John]

So daves new one has just fixed itself by using the brake method above. Which is great thanks mick! What can he/we do to stop it happening again? Is the reference 5v wire fucked?

 

[MG cup]

I would bet its basically thinking your driving round with the brake pedal pressed John while accelerating which puts it into limp mode.

 

[MicKPM]

Not quite, its a "check" method/throw back to the Sirus34 which is capable of cruise control and this 5v basically tells the ecu when the brake pedal is being used.

You've got a voltage leak somewhere which you will need to find/fix.

 

[Djw John]

Oh Lordy, that'll be fun! Thanks mick, much appreciated.

 

[MicKPM]

You'll fimd you've got 5v (normal) on the supply line and with the pedal untouched you should have 0v on the switch position line but it will be something daft like 3.8v constantly.

Welcome to my world

 

[Djw John]

Sod it, he can start it with his foot on the brakes for the next 6 months until he gets something else!

 

[MicKPM]

That may/may not work. When it see's the voltage issue after he starts driving it'll most likely throw the inconsistency fault and limit the revs to 2.5-3k

 

[Jam-Speed]

I have a 182FF and am having major issues with my limp mode. Everytime i start it is now going straight into limp mode and I can't get it out. Meaning i am not able to use the car at all. It has been doing it for a while but after a couple of good revs and turning it off and on again it would usually settle down, but now its constantly in limp mode. Anyone know what might be causing this? I have tried the brake pedal thing and also tried unpluging the accelerator pedal sensor and pluging it back in. It is producing an fault code which is for the throttle pedal position sensor.

 

[l33th3tr33]

I have a 182FF and am having major issues with my limp mode. Everytime i start it is now going straight into limp mode and I can't get it out. Meaning i am not able to use the car at all. It has been doing it for a while but after a couple of good revs and turning it off and on again it would usually settle down, but now its constantly in limp mode. Anyone know what might be causing this? I have tried the brake pedal thing and also tried unpluging the accelerator pedal sensor and pluging it back in. It is producing an fault code which is for the throttle pedal position sensor.

Might be best replacing the pedal unit.

 

[Jam-Speed]

have just bought another accelerator pedal and the plastic box on the side of it see if that sorts it.

 

[Johnpacey1]

Had a similar issue. I disconnected the battery overnight and (touch wood) it hasn't happened for over 2 weeks.

 

[MicKPM]

I have a pedal in stock just in case but I've gotta be honest... these faults are rarely due to the pedal potentiometer.

Normally poor/corroded connections

 

[Johnpacey1]

Mick, I've booked in with yourself on 9th of November to sort out this intermittent problem.

Even if I have no lights on dash will your computer log any faults or potential faults and show them up?

 

[MG cup]

He'll scope the loom if there isn't a stored fault, he seams to know his common Renault wiring faults so I wouldn't worry mate.

 

[MicKPM]

Mick, I've booked in with yourself on 9th of November to sort out this intermittent problem.

Even if I have no lights on dash will your computer log any faults or potential faults and show them up?

Yep, if the light has been on before and no-one has cleared the context data the computer will flag it. I'll also scope the pedal tracks and some other bits to prove any faults that may exist.

He'll scope the loom if there isn't a stored fault, he seams to know his common Renault wiring faults so I wouldn't worry mate.

Just emerged from a 2.5day stint with a Scenic II that had a nasty CAN fault which two other garages and Renault gave up on... I won! I wish all Renaults were as simple as these 172's

 

[MG cup]

Just emerged from a 2.5day stint with a Scenic II that had a nasty CAN fault which two other garages and Renault gave up on... I won! I wish all Renaults were as simple as these 172's

Your a better man than me, as much as I can do wiring if I sit down and periodically go through things my patience for it is non existent.

 

[lemonnobby]

Mick how did you get as good as you are.
and what was the fault on the scenic.

 

[MicKPM]

I was stupid enough to say "I'll do it" one day... the rest is just happened lol

CAN fault was a combo of R2 being under water and a naughty chafing in the rear EPB loom which allowed battery voltage to CAN L/H. Absolutely nothing worked so one garage added a new UPC and Renault just wanted to replace everything, looms and controllers.

There's still an EPB fault (no after ignition +12v but I'll fix that sometime in the week).

 

[Jam-Speed]

Changed the accelerator pedal and black box on the side of it, but alas it has made no difference. Any other ideas? As I cannot use my car and dont have another useable car did i read that it may be a corroded terminal? For some reason there is no fusebox in my engine bay, all the fuses are there bot just not in a box. I wonder if something there has corroded? Corrosion would tie in with the way the fault was very intermittent, then intermittent and now all the time!

 

[Jam-Speed]

Also can anyone recommend anyone near norwich for me to take it to if I fail to sort it myself?

 

[MicKPM]

I'm in Nottingham... I'll sort it

 

[Edges]

Just take it to Mick, he sorted a very similar problem with mine earlier this year. And saying your fuse/relay area has no box, can pretty surely say it'll be what mine was

 

[lemonnobby]

I was stupid enough to say "I'll do it" one day... the rest is just happened lol

CAN fault was a combo of R2 being under water and a naughty chafing in the rear EPB loom which allowed battery voltage to CAN L/H. Absolutely nothing worked so one garage added a new UPC and Renault just wanted to replace everything, looms and controllers.

There's still an EPB fault (no after ignition +12v but I'll fix that sometime in the week).

Oh nice. i love the old r2 connector with water.

 

[SiHow2]

Because there is a little known issue specifically with the Cups and the 5v reference voltage which occurs with a dash loom fault.Its a throw back between the brake pedal switch and the "brake on" signal to the ecu which seems to f**k up track 2. When you scope the two tracks you can see it obvioisly causing a difference between the two track signals which the ECU interprets as a pedal fault when in fact its bugger all to with the pedal and depressing the brake pedal fixes it.

So.... Excuse me for butting in on this thread but.... Could this maybe be the same issue as my 2.0t laguna!? Replaced pedal and throttle body, on throttle body replacement my fault deserted me for all of one day! The car will now not rev over 3k. As before it was bouncing at 2.5k with no throttle response. Cleaned up ecu plugs with brake cleaner and blown out with compressor (twice) removed all visible earths cleaned and greased. Reconnected and rested battery on ecu reconnected also. Fault was gone, drove 2 mile switched off and on. Fault is back!! Any help would be grateful