Scenic intermittent starting problem

[mevlar]

Hi

My sisters renault scenic 2001 (1.6 petrol) has a weird problem where sometimes it will turn on the key and run fine however most times it will take 10-20 times to start the car.

All the forums are saying its the TDC sensor which is a common fault, but a mechanic has previously replaced it. I've removed it and it looks brand new. I've also done a few tests with the multimeter and it seems to be fine.

Also doesn't seem to be the immobiliser because the the red light on the dash goes off when the ignition is on.
I've checked all fuses and swapped relays from another renault, plus the fuel pump primes when ignition is on.

Anyone have any ideas?

Thanks

Edited by mevlar on Wednesday 14th May 17:40

Edited by mevlar on Wednesday 14th May 17:44

[waseemrafiq94]

Check the positive lead wire to see if it has any breaks. Common on the new model.

[mevlar]

is that the positive lead from the sensor to ecu?

Is the bet way just to make a new connection with new cable because its wrapped up and hard to trace.

thanks

Edited by mevlar on Wednesday 14th May 20:12

Edited by mevlar on Wednesday 14th May 21:05

[waseemrafiq94]

Its the positive lead from the battery. Water ingress through time makes the lead go green and u sometimes get a connection. Its common on the 53 onwards models.

Check the lead, follow it round and look for any discoloration

[mevlar]

The furthest I could follow it is to the ecu can't see where it goes after that. is there are quick way to find the other end near the battery.

Thanks

Edited by mevlar on Wednesday 14th May 21:14

[Collectingbrass]

Before getting into the complex stuff, have you checked the basics? (something I fail to do _very_ regularly)

I'd swop the battery and starter motor first, as from your symptoms and car age that's what I'd put money on. Also should be an easier fix, though it is french...

[mevlar]

Tried new battery, don't have another starter motor to try but it sound find to me. I think it is the positive cable, but am unsure how to trace it back to the battery.

I've pulled the plug off the ecu and put a multimeter on the pin which beeps so I know its the right one - but its stops here? If i put the plug back in the ecu I can't find where it goes.

I search the internet but can't find a wiring diagram for the vehicle.

Thanks

[ch427]

There is a loom problem on the crank position sensor on some renaults so worth checking this out, i believe a modified section of loom is available.

[Steve H]

How about if we start guessing and try to avoid throwing too many parts at the car based on guesswork.


Does it still crank OK when it won't start, i.e. turn over at a decent speed? If it does then it's unlikely to be the main power cable or starter.

The modded wire for the crank sensor is designed to work with the later oe replacement sensors as the pins are plated with a different metal, those wires don't usually corrode and the ones that do are just as likely to have the car cutting out as not starting in the first place.


I'd suggest that if it plays up as often as you suggest then your best investment would be in a decent diagnostic guy, for far less than the cost of a starter motor you could probably get a proper answer.

[mevlar]

ye it cranks over okay at a decent speed just doesn't fire.

May look at taking to a garage.

[Steve H]

A local diag specialist would be a better bet than your average garage if you have one.



But then I would say that

[mevlar]

fixed it. There was a loose connection in the large white block connector. It's behind the fuse board under the bonnet. When the block connectors were pushed together the pin was not making a contact. Engine started behaving fine after this.

Thanks for your help guys.

PS. Was a light yellow cable on one side and a white cable on the other.