toto25

Member
hi ,
my td4 starts very well when cold, and after driving then stopping the car in very hot weather (+30) the car does not start (starter does not turn).
Do you have any idea of the problem?
I also noticed that the fan in ecm spins when it refuses to start. This fan seems to be controlled by a bwm 35°c temperature sensor located in the ecm box.
Could it be the cause of the breakdown?
do you know where the air is taken that is sucked in by this fan
no error code on suitcase.
pipe air temperature: 44°c

best regards
 
The fan is there to keep the ECM cool. It's not related to or controlled by the ECM, it's completely independent of any electronics altogether.

Have you checked the small trigger terminal on the starter for corrosion? This issue doesn't create a click from the starter.

It's also not uncommon for the starter contacts to burn out. If this is the case, the starter will click, and do nothing else.
 
thank you for your help, the solenoid is not oxidized and does not click at all.
Have you checked that you are getting voltage at the small starter terminal when you turn the key to the start position?
Have you checked the start control relay (2) in the fuse box is A working, and getting power when you turn the key?

20220603_151300.png
 
thanks a lot for your help Nodge68 ; I will look tomorrow morning.
an idea came to me: Could the inertia button be the problem?
best regards
 
hi , Nodge68
The relay seems to be ok, I measured 100 ohms when hot. And also swapped two relays. But meaning effect. Engine still won't start warm.
thank
 
I measured 100 ohms when hot. And also swapped two relays. But meaning effect. Engine still won't start warm.
Have you tried to jump the start relay, to make sure the starter is actually working? (Make sure it's not in gear!)

If the starter is working, then have you checked you're getting the start signal at the relay, when you turn the key to the start position?

If not, have you checked the ignition switch is actually sending out the start signal?

The ignition switch is known to fail sometimes.
 
no i have not make this test ,
engine cold all is ok
To me it suggests that something is failing when it's hot. So the starter being bolted to the engine gets hot, so that would be my first thing to check.
Next would be the start circuit from the ignition switch to the relay.
 
Hi, whilst some trys to crank it give the starter motor a tap with a piece of wood (chair leg or similar). As @Nodge68 says it's a good place to start. If it cranks/starts check the battery post cable is tight if it still plays up then remove the starter motor & replace the contacts inside with the kits off eBay.
 
Yes that's the kit but first give the starter motor a tap whilst someone is trying to start it, it could just be the post on the starter motor is loose.
When mine had this problem I got the kit then stripped the motor but it only needed the contacts inside cleaning, it's done over 20,000 miles since then & I still have the kit to fit:). The vehicle has about 173,000 miles on it in total & still the original starter motor !
 

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