Hello,

 

Recently I noticed increased revs on idle every time I stop with engine heated on operational temperature. Revs on 950 rpm like regenerating

but every time I stop.

Then checked with VCDS and found this error :

01117 - Generator Terminal DF Load Signal: Implausible Signal

 

P1503 00 [096] - Implausible Signal

Car is fabia mk2 2010, 1.6tdi 77KW cayc engine code.

Local workshop changed voltage regulator and there is no error any more. 

But high revs on idle remains like before repair.

Googled and found it colud be because of voltage issue when engine tries to get enough power through higher revs.

I wonder would it could be some problem with new voltage regulator ?

Thank you...

Most likely a broken wire or bad connection, from mk1 experience.

Follow the brown/red wire from the 2-way connector at the alternator, and it will change colour to violet/green at pin 3 of an 8-way connector pair at the front left of the engine bay (left as seen sitting in the car looking forward).  Check connectivity between those two connectors, and wiring for breakage anywhere on that run. 

If that seems OK, check the run of the violet/green leg from the 8-way to engine ECU pin 65.

 

Edited 17 June, 20214 yr by Wino

Thank you Wino, I will try to check this as soon as possible and I will write the results

Wino I did not try your recomendation jet because I was not sure how to do it. I was afraid of disconnecting ECU connectors and how I will manage that. But I try to replace voltage regulator but with no results. Even this voltage regulator, claimed as original Bosch has 0.5 V lower voltage than the one fited by local garage. I plan to check voltage on alternator connector while engine running, I figured to use little needle to go through wire insulation and check voltage. Jet not sure how to disconnect ECU connector and other connector you mentioned but will try for sure...

How to undo VW wiring connectors. - YouTube

Dear Wino, yesterday I managed to check this in a way you recommend. I disconnect ECU connector, upper one and found pin 65, mark it with needle. Other end of multimeter connect to red pin on alternator connector and there is no connection at all.

Other connector you mentioned not sure I identified correctly. One I found on left side as seen from cabin has 13 pins and on it there is no connection with alternator connector. I posted some pictures.

I'll draw you a picture to explain. Maybe 1 or 2 hours from now.

It's definitely an 8-way connector pair that you're looking for, not 13 or 14.

 

 

Thank you very much for your effort... I am very thankful to you, I will check today after work again...

Tried to locate this connector yesterday after work but without success. I can't find that thing in engine space. Found on google that it might be under engine and next step will try to take off plasctic cover under engine to see what can I find...

I wonder if @DieselMonte knows where this connector is? He seems like a man who will have explored his engine bay thoroughly. 

49 minutes ago, Wino said:

I wonder if @DieselMonte knows where this connector is? He seems like a man who will have explored his engine bay thoroughly. 

I'll give a look later on my car.

My car did the high idle thing before when I wasnt driving it much, I think its just a regen. Was told it could also be because the car thinks the battery is low so its keeping higher revs to charge itself. Since i've had the dpf removed its done the high idle thing exactly once.

If its a connector that size my mk1 has one just like that on the front of the engine, (I want to say near the oil filter housing?) and it goes to the alternator iirc. I imagine its going to be in a similar spot on my mk2.

 

Of the remaining 6 ways on the connector, 4 go to the charge pressure/intake temperature sensor (MAP sensor), and 2 to the A/C compressor control solenoid valve, as far as I can see from wiring info.

Edited 16 July, 20214 yr by Wino

I'm guessing the connector I circled is the one ehod has the photo of? Near the battery?

I don't know if this is much help But I started at the brown wire at the alternator plug (see second pic) and tried to chase it back. From what I can see its going down and under some coolant hose in behind the intake manifold. I lost it after that but it must be pretty low on the engine, guessing you'll see it if you can get under the car and get off the undertray. If I can get out i'll put my car over the pit and take off the undertray and look for it.

Dear friends, today I managed to locate connector. It was under engine on same side as battery. After I disconnected connector I found broken wire on pin 3 as Wino assumed. I will post pictures. Did not tested car yet as I just finished this job but I hope it will be ok. I will post the results. And I can not find words to express my gratitude to both of you. You are great guys, thank you both 

Just to confirm, problem solved, engine heated up and still on 750 revs .....

ehodzicus78 , I have the exact same problem, i changed the regulator reley from the alternator, and allso i went to remake the alternator because it didnt charge the battery no more, but after i done this and the charging is at 14,45 V, i have the error p1503 and it revs at 1000 rpm sometimes, even if the engine is worm at 90 , as i cheked the cable of the alternator ive found that the cable was eaten by the ac ventilator because it hanged down from its support, so i managed to repair the cables by soldering them and put thermo cover on them, after i done the repairs i still have the same issue with the revs at 1000 rom, so i will check this conector as u did and hopefully il fix the problem. 

Glad to hear that your repair methods are suitable for the job, that photo of the uninsulated brass connector made me shudder.

Well, today i cheked the cable , and its fine , the problem is that i have changed an alternatoe , at the bigining it was charging 14.1 V after 2 km the battery light from dashboard just blinked a few times , after i stoped and cheked the the charging again , i had no charging from the alternator, and the alternator its hot... i fidnt cheked the battery , is it possible the batery to be in short and when the alternator was charging to make a short and to ruin the alternator???

Unlikely, alternators do get hot, that's why they've got all those slots in the casing to cool them down.

 

It's possible that the charge controller itself is faulty resulting in the battery light blinking on and off.

ok i understand, but at the old alternatoe i changed the relay and the interior thing in the alternator, and i cheked and it was charging 14.3 V , but the issue is that the car stays at 1000 rpm while staying or if i drive like 10 minute andd then stop , it keeps that 1000 rpm , and i i have the same error.

IMG20230914205518.heic

Have you checked the DFM wire all the way back to the engine ECU?

If not, tell me your engine code if you want info on where to look.

Unplug the 2-way connector from the alternator and measure the voltage on each wire with ignition switched on.

That should quickly establish if either is broken.

I have changed the alternator with a second ha d one , and  at the beggining of like 10 minute it was charging 14.3 V , after 10 minutes of driving the batery light pup up on my dashboard , and when i stoped in the parking lot , i cheked again and no more charging... i cheked the fuse from the big cable from the alternstor and its ok , i cheked the pin at the clips for the charging relay and no voltage , so i think its the cable.