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RawUmber
Samba Member
Joined: June 23, 2019
Posts: 303
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 Posted: Tue May 10, 2022 5:07 am Post subject: Re: Idle Control Module issue (high idle) & cheap fix |
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| tanhis wrote: |
| Can someone confirm is this the correct resitor as I have the same burnt resitor in my digijet 2.1 DJ 251 907 739 A on top of burt NTE185. |
If the control unit is a 251907393A (you have a '739' in there), the phillips driver in your photo is pointing to a diode. If you like NTE, their sub for it is NTE125. Unlike resistors, the polarity/orientation of diodes and transistors is critical. You can use Goodie's photo as a reference:
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tanhis
Samba Member
Joined: July 23, 2005
Posts: 658
Location: Rauma Finland
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| Posted: Tue May 10, 2022 5:20 am Post subject: Re: Idle Control Module issue (high idle) & cheap fix |
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| RawUmber wrote: |
| tanhis wrote: |
| Can someone confirm is this the correct resitor as I have the same burnt resitor in my digijet 2.1 DJ 251 907 739 A on top of burt NTE185. |
If the control unit is a 251907393A (you have a '739' in there), the phillips driver in your photo is pointing to a diode. If you like NTE, their sub for it is NTE125. Unlike resistors, the polarity/orientation of diodes and transistors is critical. You can use Goodie's photo as a reference:
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For some reason the quote shows randomly two different images.
This it the burnt resitor that I am talking about.
_________________
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RawUmber
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Joined: June 23, 2019
Posts: 303
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| Posted: Tue May 10, 2022 5:39 am Post subject: Re: Idle Control Module issue (high idle) & cheap fix |
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| I see. That's a 56Ω resistor, and it's most likely OK. After manufacture of the unit, they coated the whole board in a conformal coating to protect it from moisture. When the resistor gets hot, it tends to discolor the coating like that. You can put an ohm meter on both terminals of the resistor... should see 56, give or take a few % (within 10% is spec). If it tests good, it's unlikely to be your problem. |
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tanhis
Samba Member
Joined: July 23, 2005
Posts: 658
Location: Rauma Finland
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| Posted: Tue May 10, 2022 5:46 am Post subject: Re: Idle Control Module issue (high idle) & cheap fix |
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| RawUmber wrote: |
| I see. That's a 56Ω resistor, and it's most likely OK. After manufacture of the unit, they coated the whole board in a conformal coating to protect it from moisture. When the resistor gets hot, it tends to discolor the coating like that. You can put an ohm meter on both terminals of the resistor... should see 56, give or take a few % (within 10% is spec). If it tests good, it's unlikely to be your problem. |
Thanks. I will measure it but I am going to get spares an will buy that as well . And my main problem can be seen here.
_________________
-58 Typ2 ambulance
-62 Typ 34
-65 Typ 34
-73 411 variant all metal custom
-69 typ 2, 9 seater
-89 vanagon camper conversion matkaaja
-08 3.0tdi phaeton |
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RawUmber
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Joined: June 23, 2019
Posts: 303
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| Posted: Tue May 10, 2022 6:21 am Post subject: Re: Idle Control Module issue (high idle) & cheap fix |
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That burnt looking transistor drives the Idle Stabilization Valve. From the looks, it's a good plan to replace it. So how did it get that way? One possibility is a bad valve. You might do some tests on it. Disconnected, the valve's terminals usually measure somewhere between 4-8Ω [edit: Bosch says ~10Ω, YMMV]. If it measures OK, you can momentarily connect the terminals to a little 9V battery and it should click open. If the valve was shorted (eg, 0Ω) or the internal actuator stuck, the transistor would get hot trying to operate it, eventually failing. That said, the transistor can go bad for other reasons.
Last edited by RawUmber on Tue May 10, 2022 9:06 am; edited 1 time in total |
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tanhis
Samba Member
Joined: July 23, 2005
Posts: 658
Location: Rauma Finland
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| Posted: Tue May 10, 2022 6:30 am Post subject: Re: Idle Control Module issue (high idle) & cheap fix |
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| RawUmber wrote: |
| That burnt looking transistor drives the Idle Stabilization Valve. From the looks, it's a good plan to replace it. So how did it get that way? One possibility is a bad valve. You might do some tests on it. Disconnected, the valve's terminals usually measure somewhere between 4-8Ω. If it measures OK, you can momentarily connect the terminals to a little 9V battery and it should click open. If the valve was shorted (eg, 0Ω) or the internal actuator stuck, the transistor would get hot trying to operate it, eventually failing. That said, the transistor can go bad for other reasons. |
I had to order the transistor. As local electric store did not have it on stock.
And I did measure the burnt looking resitor and it was good.
And next I will check the function of the valve.
Btw as I am going to take my welder and related tools out. Would it be wise to replace the capasitors on the same go as at least one looks a bit chubby.
_________________
-58 Typ2 ambulance
-62 Typ 34
-65 Typ 34
-73 411 variant all metal custom
-69 typ 2, 9 seater
-89 vanagon camper conversion matkaaja
-08 3.0tdi phaeton |
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RawUmber
Samba Member
Joined: June 23, 2019
Posts: 303
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| Posted: Tue May 10, 2022 7:20 am Post subject: Re: Idle Control Module issue (high idle) & cheap fix |
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| tanhis wrote: |
| Would it be wise to replace the capasitors on the same go as at least one looks a bit chubby. |
My guess is the chubbiness is an illusion of the conformal coating, but can't say for sure. If the bottom terminals of the capacitors are not shorted to each other (ie, ~0Ω), I wouldn't bother replacing them at this point, but it's your call. Obviously, if your Idle Stabilization system doesn't work, something is at fault, but I would start by replacing the known bad components and work up from there. |
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tanhis
Samba Member
Joined: July 23, 2005
Posts: 658
Location: Rauma Finland
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| Posted: Tue May 10, 2022 11:47 am Post subject: Re: Idle Control Module issue (high idle) & cheap fix |
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I need to borrow a better multimeter that has Farad measurement as a option. But at least the capasitors were not short circuit. And the coating is pain in the ass when doing measurements like this.
As I got my hands dirty I also checked the function of the trottle idle switch it worked but it has 1.4 ohm resistance when closed. What do you think will this cause an issue.
_________________
-58 Typ2 ambulance
-62 Typ 34
-65 Typ 34
-73 411 variant all metal custom
-69 typ 2, 9 seater
-89 vanagon camper conversion matkaaja
-08 3.0tdi phaeton |
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RawUmber
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Joined: June 23, 2019
Posts: 303
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| Posted: Wed May 11, 2022 9:47 am Post subject: Re: Idle Control Module issue (high idle) & cheap fix |
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| I think the spec is ~0Ω, but 1.4Ω is likely OK. |
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