Starting fault (common i know)

[Barton1806]

My 172 has been stored in my garage and the battery went completely flat. Fitted a new battery and now it will not start :-/

Turn key to position 2, wait for lights on dash to clear, turn key = nothing, just clicking of relays
Turn key straight to position 3, car cranks and automatically stops cranking once the dash lights then go out.
The STOP light stays illuminated on the dash the whole time I try to start it.
The immobilizer light flashes and when I insert the key and crank it, it illuminates constant & stays on.

I messed with the relays under the dash and sometimes it will crank and cut out as said above but sometimes it will not crank at all either way.

Anybody have an idea? or any Clio gurus in the South Wales area?

Thanks in advance

 

[1hpclio]

My mates 182 did that yesterday, open bonnet to find a broken earth, but i think battery light was on too. Worth a try

 

[da rok]

Check all the fuses as well, give everything a wiggle

 

[Rone]

Constant red immobilizer light after turning the key means that the ECU and UCH datalink is not establishing a connection, although it's trying. The ECU does not have the permission to fire the engine. The ECU stops the engine from cranking whenever the immobilizer circuit in the ECU has reached the conclusion that the authorization is not coming from the UCH.

A lot of reasons why this could happen. Apparently your ECU is receiving power because you engine cranks at least occasionally. Also if your immobilizer light is flashing with a normal pulse whenever there are no keys in the ignition lock, this means that also your UCH is receiving power. So my bet is on a broken wire between the ECU and the UCH. I've heard that there is some constant pull force on the thin wires, the place where the wire breaks is supposedly located some two inches deeper into the dashboard from the place where the wiring loom separates into multiple smaller branches, probably was in the cabin end of the wiring loom - can't recall for sure though.

But, considering your stuff worked when you drove it into the garage, this issue sounds pretty cryptic. Maybe some more troubleshooting ideas would be of use.

 

[Rone]

After doing some more reading on this topic, it appears that other possible causes are the key fob failing (probably not as you are getting the constant red immo light), UCH failing (high probability in your case), a broken wire anywhere in-between the UCH and ECU as I stated above (moderate probability in your case), and, a relay failure in the engine bay fuse box (high probability).

As I first step, pop the bonnet and remove the engine bay fuse box cover. You should see 2 to 3 small (there are two sizes of relays: small and big) relays. Pull them out and put them back in, in different sockets than they were. After this go try start the car and see if there is any change in the behaviour of the immobilizer light. If this procedure has no effect, you need to get the car hooked up to a Renault CAN adapter called Clip. It uses the Renault proprietary protocol and can run tests on the continuity of wires of the wiring loom and if this test gives all systems go, next the Clip is used to check whether the UCH can read the key code via the ignition lock from the key or if the UCH itself is malfunctioning. If any of your friends have the Clip ask them or bite the bullet and go to official Renault dealer to have it diagnosed.