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Volkswagen Rabbit, Jetta, Scirocco, Convertible: 1975-1984 (A1) 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp


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Last Post: Mar 30, 2010 9:39 PM Last Post By: ArchivalAudio
ArchivalAudio

Posts: 120
Registered: 04/29/07
84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 27, 2010 7:58 PM
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Hello,
on Thursday I drove south on I-5 and got off in Medford as I often do a 200+ mile ~ 3.5 hour drive,
however at the top of the freeway off ramp my h2o temp sensor was pegged all the way to the right at HOT!
so I cranked up my heat and blower motor opened the windows.

It appeared that the electrical radiator fan was not turning on. I replaced the thermo-switch in the radiator.
still the gauge would so over hot
I rewired the fan - in a panic with a 30 amp fuse direct to the battery, via the thermo switch, still the fan did not come on.
I have since check the temps with a potentially inaccurate candy thermometer in the coolant reservoir tank, never above about 190F the thermo switch I installed was a 92C on and 87C off -as spec'ed
92C = 197.6F
and 87C = 188.6F
temps seem under those limits even when the h2o temp gauge reads HOT!!!

on my way back home - I Stopped a number of times at once stop I removed and replugged in the X- Relay and the Blower/heater motor fuse.

after that I got normal readings in both the temp gauge & Fuel gauge which had both been pegged off the charts.

I stopped in Eugene for a meeting.
then after I Started the car - once again super over the top fuel and temp readings.

I also notice that my X-Relay was super HOT! almost too hot to touch
the Horn appears not to function but I could hear the relay click when the horn is depressed - also the horn relay was running super hot!

I have a couple of spare relays - in my car at all times and even swapped them out for different ones- still totally hot!

it appear I have some strange short issue

I saw that there could potentially be an issue with the voltage stabilizer?

but I doubt that would explain the super HOT relays

any one have any thoughts? or Ideas?

More info needed? - clarifications?

please help!

thank you
--Ian

Edited by: ArchivalAudio on Mar 27, 2010 8:02 PM
ArchivalAudio

Posts: 120
Registered: 04/29/07
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 28, 2010 12:49 AM   in response to: ArchivalAudio in response to: ArchivalAudio
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FKH161?
any input? please?
FKH161

Posts: 7,610
Registered: 12/29/05
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 28, 2010 2:03 AM   in response to: ArchivalAudio in response to: ArchivalAudio
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I was gonna let someone else have a stab at it.... I too thought about the voltage stabilizer, but not sure.

Check the easy stuff first, charging voltage & amperage and report back... as well as all the usual connections (battery, grounds etc).

Hot relay(s) and dash gauges could be connected, but might not be.
tcovenant2000

Posts: 1,761
Registered: 12/09/03
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 28, 2010 10:33 AM   in response to: FKH161 in response to: FKH161
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I would guess voltage stabilizer. The device may be shorted from the 12V (input) side to the ground side internally. It would then pull a ton of current, which would cause the x relay to get hot. It may get worse with heat. If so, it's also likely it's shorting 12V to the output side which would cause the gauges to go too high.
One easy way to test it would be to pull the fuse to the stabilizer. Connect an ammeter across the fuse terminals and turn on the car. (Do this after you've driven enough that the gauges are whacky). Then record the current flow while the gauges are whacky. You'll also need to do this while the gauges aren't whacky to get a reading of what's normal.
Off the top of my head I don't know what else runs off that fuse, but shouldn't be much. There should be very little difference between whacky and non-whacky readings.
Be sure that your ammeter is capable of at least 10A or you could pop the fuse in the meter.

Thomas
ArchivalAudio

Posts: 120
Registered: 04/29/07
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 28, 2010 10:51 AM   in response to: tcovenant2000 in response to: tcovenant2000
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Thank you
however is there an easy way to identify the fuse for the voltage stabilizer? I don't believe it's listed that way on the fuse block.

Also I am wondering where the voltage stabilizer "lives" it would appear it is associated withe the instrument cluster, or at least test terminals on on the rear of the cluster.
if I need to remove the cluster, I won't really be able to keep it plugged in and test it. so obviously I'm confused. am I missing things?

thanx
--Ian
FKH161

Posts: 7,610
Registered: 12/29/05
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 28, 2010 1:31 PM   in response to: ArchivalAudio in response to: ArchivalAudio
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Attachment VS001.jpg (378.6 KB)
The VS gets power from the ignition switch (circuit 15 ignition on).

See attached images of stabilizer location.

Edited by: FKH161 on Mar 28, 2010 1:36 PM

Your cluster might look slightly different
ArchivalAudio

Posts: 120
Registered: 04/29/07
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 28, 2010 4:26 PM   in response to: FKH161 in response to: FKH161
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FKH161,
thank you
for the photos, that does help

is there a fuse that corresponds to the voltage stabilizer?
or can the voltage stabilizer be replaced? I am handy with a solder iron if something needs to be resoldiered in place?

I saw in the service manual a bit on how to check it for resistance etc.
if it gets power from circuit 15 - is there a potential issue of conflict with the X-Relay or some other power/voltage issue with circuit 15?

it would seem that potentially it's getting to high a voltage or that the voltage stabilizer is unable to "stabilize" that incoming voltage. is that correct?

thanx
--Ian

Edited by: ArchivalAudio on Mar 28, 2010 4:26 PM
FKH161

Posts: 7,610
Registered: 12/29/05
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 28, 2010 4:39 PM   in response to: ArchivalAudio in response to: ArchivalAudio
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No fuse that I can see (but I'm looking at an '85 Jetta Diagram).

Attached VS testing page from Bentley A2 Manual.

The A2 Manual can be downloaded and installed/activated for $109.95
ArchivalAudio

Posts: 120
Registered: 04/29/07
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 28, 2010 7:42 PM   in response to: FKH161 in response to: FKH161
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Thanx

I have the paper copy of the bentley manual 1986 edition: on Page 64 of my manual it shows how to test the voltage stabilizer in photo - 90-240 they mention that the VDO and Motometer Voltage stabilizers are interchangeable. though not how to change them.

So until today - I would have said that when my car is running with no or little electrical load at idle voltage is about 13volts, and rises to around 14 when they engine RPM is increased.
however today (just after I got home from work a few minutes ago)

I check the battery voltage with the car idling it seemed to be about 13 volts.
however when I revved the RPMs up, it jumped to 16 & 17 nearly 18 volts, it may have surged to over 18volts.
that seems very weird the remain bosh alternator is barley over 1.5 years old. I even looked at the brushes last week and they seemed fine.

I have had some wiring issues in the past and I have rewired many leads from the alternator to the battery and added extra redundant grounds, and - last week replaced the V-Belt as my old one appears to be slipping causing the battery light on the dash to occasionally flicker - at idle. Sometimes I would hear the belts squealing under-load while driving and - too occasionally the battery light would flicker.

I am thinking that the higher than 14 volts spiking is abnormal and bad., but what would cause that?

does the voltage stabilizer moderate all voltage in the entire car?

It won't be until tomorrow that I could potentially take out the dash instrument cluster

  • It appears that I need to have the cluster still wired in but tipped back enough to access the terminal points in order to have power to it, seems tricky, but somehow can be done.?

this is getting weirder all the time.

thanx
--Ian

RickW

Posts: 718
Registered: 02/16/05
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 29, 2010 10:48 AM   in response to: ArchivalAudio in response to: ArchivalAudio
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Hello, Ian

Sorry for chiming in so late, though it looks like you've had a lot of excellent suggestions so far as to how to go about troubleshooting.

As for the book, I believe you're referring to page 64 of section 6, Electrical System, of the Rabbit and Jetta Service Manual, covering 1977-1984?

I have a current printing of the book on hand, and the information you quote looks to be the same, so there hasn't been an update to it. As for changing the voltage stabilizer, the photo suggests it's held in by a couple of screws, nothing more. Unfortunately, that's all I have to go by.

The only other thing I can suggest is following the wiring diagrams in the book and trace what all the related components have in common to find the short.

Rick W
Bentley Publishers
ArchivalAudio

Posts: 120
Registered: 04/29/07
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 29, 2010 8:06 PM   in response to: RickW in response to: RickW
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Thank you to everyone.
Thanx as always to FHK161
and to RickW
et al

I think I actually figured it out! :)

On my way to work this am- in the dark I turned on all of my electrical accessories, to use as much power as possible- mostly the gauges were ok.

Again this afternoon I checked the voltage with everything on at idle it was around 12.93v not bad- then I revved the engine it read about 13.5v - then turned off all power consuming accessories ( headlights, fog lights, fuel filter heater, stereo, blower motor, wipers) and checked the voltage when revved- it was over 16 and 17v

shut her down when the gauges showed over hot and full.

I have a buddy that works on VW diesels, he ordered me a new BOSH brush / voltage regulator part # 1 197 311 090. Which cost about $38 - I replaced it

That did it! --- voltage at 14.03v while revving the engine. temp and fuel gauge normal!

(why the voltage regulator on the brush pack would go out on a re-manufactured BOSH alternator after only ~1.5 years is baffling)

He also let me have a pre-used voltage stabilizer that we bench tested and seems to spec out within tolerances. Which I plan on replacing for good measure when I get a day off work to take out the instrument cluster with out any stress.

we looked at a few different clusters and where and how the Voltage Stabilizers just plug in and are secured by a single screw- totally easy! and I have one that is with in the 9.5 to 10.5 volt tolerance stated in the manual.

Thanx to Bentley for continuing th make the mannuals available - eve if parts are gettign more difficult to find for my 1984 Rabbit Diesel!

This is the most useful VW forum for trouble shooting out there thanx to everyone for sharing their knowledge!

--ian

RickW

Posts: 718
Registered: 02/16/05
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 30, 2010 9:56 AM   in response to: ArchivalAudio in response to: ArchivalAudio
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Hello, ArchivalAudio

Glad to hear you got it figured out.

"(why the voltage regulator on the brush pack would go out on a re-manufactured BOSH alternator after only ~1.5 years is baffling)"

In my experience, there is no guarantee with rebuilt parts. I have had Bosch remanufactured alternators fail on me right out of the box, whereas the original Bosch alternator remanufactured by the VEHICLE manufacturer checked out OK. So, your situation isn't too surprising. It happens. Luckily, a new voltage regulator seems to have fixed your problem.

Rick W
Bentley Publishers
tcovenant2000

Posts: 1,761
Registered: 12/09/03
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 30, 2010 6:59 PM   in response to: ArchivalAudio in response to: ArchivalAudio
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Yep. Soon as you said batt volts went to 18 I thought "voltage regulator". Most people don't see the gauges get whacky, they see the lights get REALLY bright when at high RPM.
Glad you got 'er fixed. The brushes get replaced, but I doubt the stabilizer itself gets replaced on a reman...but I don't know for sure. At any rate, ESD could have damaged it through no fault of yours, or many other reasons.

Thomas
ArchivalAudio

Posts: 120
Registered: 04/29/07
Re: 84 diesel rabbit -Temp pegged hot! fuel gauge over full? normal engine temp
Posted: Mar 30, 2010 9:39 PM   in response to: tcovenant2000 in response to: tcovenant2000
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It's lucky that nothing fried!
The big solid tip off was that the dash lights were very bright, and my headlights were bight, but I also saw them all dim a few items on my way to work. So I really thought it was the voltage regulator on the alternator, and not the voltage stabilizer on the back of the instrument cluster.

I do still plan on replacing the Voltage Stabilizer on the instrument cluster that spec'ed out within the correct tolerances. As I need to replace my headlight switch any way- as occasionally my headlights just turn off while traveling down the road- and highway at 7omph at night - not a great feeling... all the other lights stay on, and luckily I have "fog" lights installed and they stay on.
thought It may be also a high beam switch issue... but that's a whole 'nother story.

Thank you for all the support and sharing information from everyone!

After all I got my Rabbit from a farm in Monroe OR where it sat with a seized engine for over 6 years - collecting water, as you may know it rains a lot in the Willamette Valley!- but with much advice and questions answered here- I rebuilt the engine and have problem solved a number of issues.

Peace
--Ian

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