temp and batt light flashes intermitantly. - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

• temp and batt light flashes intermitantly. by Smokey Eddy on 15 Feb, 2009 19:26
• What causes the temp light to flash for periods of time and then go away?
  I changed the sensor that sends to the gauge. The level sensor in the expansion tank is fairly new. (less than 5,000km old)
  and my battery light will dimly flicker now. Recent since head replacement.
• #1 by CODE4LS1 on 15 Feb, 2009 21:29
• My Caddy does the same thing ('84 Jetta dash swap), and every once in a while my temp light will flash for a few seconds and go away.  When there is no load on the charging system, my batt light will flicker at idle, but once the cooling fan comes on the flickering light disappears.
  
  To answer your question, I had some probs with the + battery cable connections being dirty.  When I would drive at night w/the lights on and the cooling fan came on, one of the cables would arc and everything would go dead (no lights and engine would die).  Once they were cleaned (taken apart at the white connectors), I don't see that prob anymore.  Hope this helps.
• #2 by Smokey Eddy on 16 Feb, 2009 03:54
• I have new lead terminal leads
  I think im going to replace the brush assembly in the alternator and/or voltage regulator. But im still angry with the temp light. It's flashing 90% of the time.
  
  
  Maybe i can replace the wire that leads from the alternator to the battery/starter where ever it goes with some shielded welding cable or something. I'm afraid of how it connects to the alternator though ... it has that weird plastic cap over where it enters the alternator.
• #3 by zukgod1 on 16 Feb, 2009 07:36
• I think your on the correct path Ed.
  
  I replaced the wire from the alt to the batt with some 1/0 as well and same from the batt to the starter. My alt light doesn't come on at all once its excited after the first start up.
  I used some Amp wire I had left over from previous years. I knew those small pieces would be handy some day.
• #4 by clbanman on 16 Feb, 2009 07:54
• Ed, if it's just since your head replacement, what did you do on the threads of the sensors going into your head?  Lots of sealant or teflon tape has been known to insulate them enough to prevent proper grounding of the sensor.
• #5 by Vincent Waldon on 16 Feb, 2009 08:24
• Some random thoughts:
  
  Grounds grounds grounds... weird electrical stuff coupled with dimly-flickering alternator lights is almost always grounds.  :wink:
  
  I usually start electrical gremlin troubleshooting with "Extreme Makeover: Grounds Edition": battery cables , clamps, ground to the chassis, ground to the tranny, star-ground under the dash... they all get demolished and rebuilt, with lots of sanding and a thin coat of dielectric grease to keep 'em from re-offending.
  
  Another trick I sometimes try is the ole "run a bypass on the plasma conduits Jordie" move... using booster cables make some temporary big grounds:  case of the alternator directly to the battery, battery directly to the engine block or tranny. If the alt light changes brightness you know you're on to something.
• #6 by zukgod1 on 16 Feb, 2009 08:28
• Ah yes, I did add 2 ground's as well when I did the alt cables. Ran one to the body and one to the engine. Same wire as the alt.
• #7 by Smokey Eddy on 16 Feb, 2009 11:21
• Thanks for all the replies!!!!
  
  I have 1 big mother of a ground going from the battery to the trans and i took the old pretty big gauge copper ground that USED to do that and i grounded it to the body. I should probably try and sand some more of the paint off and re-attatch. Where is the "star ground" under the dash? I have a strong feeling i moved that by accident doing my gauges and dash lights.
  
  clbanman, yeah i put some antizieze on my oil temp sender to stop it from leaking.... The temp light that obviously doesn't apply though as i couldnt have put anything on it . I think i'll try and make/find a gasket for that oil temp sender & clean it off as well as sand down that body ground and trans ground. Then if that doesn't do it find some welding wire or say goodbye to my really old jumper cables and use one of them for the alternator.
  
  Thanks guy! I would just like to know what this star ground is though! That likely needs attention eh Vince.
• #8 by Vincent Waldon on 16 Feb, 2009 11:46
• Quote from: "Smokey Eddy"

  
  Thanks guy! I would just like to know what this star ground is though!

  
  
  It varies from chassis to chassis and year to year, but over by the fuse block there is usually a master ground block with a whack of brown wires running to it.  IIRC on MK1/2's it's often just a big brass circle that lots of spade lugs plug into, on the MK3s it's brown plastic that the OEM connectors plug into.
  
  In any event, it's how most of the stuff under the dash gets grounded... including the cluster, brake warning lights, etc.  It's usually just screwed into the chassis and when it gets old/rusty/etc all kinds of interesting rogue paths form for current to flow thru.
  
  Wouldn't it be great if we could actually see electrons?!!   :wink:
• #9 by Smokey Eddy on 17 Feb, 2009 02:49
• I've always wanted to see electrons vince. You should come on down to UBC and see the particle accelerator. You can't exactly "see" anything but the detectors do! and if you understand the mumbo jumbo the nerds there are talking about it's pretty cool stuff.
  
  
  None the less! back to much more useful and important  :roll:  matters. I got day plates again for the 17th so i drove to the Gf's house and back at midnight. The batt light is on more brightly and steadily now. The temp light is still flashing intermitantly. When the temp is reading in the middle the light stops flashing. Sometimes the needle just drops and the temp light flashes again. sometimes the temp reads hotter than the middle and the light flashes. Sometimes it reads normal and the light flashes.
  
  I tried to see if hte coolant temp was going hot and cold so i gave er up a big hill in 4th and got the EGT to 1,000F for at least 15 seconds and the coolant temp gauge didn't seem to change accordingly.
  
  It's really really pissing me off. I checked the ground to the trans and it's clean metal on clean metal. The body ground probably could do with some sanding (wire wheeling) but this coolant gauge and light is just pissing the heck outta me. the constant flashing and constant flickering of the batt. light is so annoying. Especially when your friends keep reminding you "there are lights flashing... should we really be driving this? is this safe" makes me feel pretty ... crappy.  My friend refused to get in it to go for a drive because he was convinced a piston was going to fly through the hood and kill him somehow. This was coming from my friend who didn't know the difference between the cam cover and transmission. He asked which one the pistons were in.
  
  Since i've had the car the temp light/gauge has been royally screwed and sensor replacement, expansion tank replacement, cap replacement, water pump replacement and head replacement have all YET to solve the mystery of my phantom temp gauge and idiot light. I can't really post pictures... maybe i'll ask a friend to hold a camera taking a video while i drive. the gauge never stays still... it's always slowly changing.  I don't really know what other wiring there is other than the GP and temp sensors, the level sensor and ... that's it... there isn't anything else. If the GP sensor is bad will that trigger the light to flash for periods of time?
• #10 by Smokey Eddy on 19 Feb, 2009 21:39
• Any ideas on the gauge being so retarded?
• #11 by Smokey Eddy on 17 Mar, 2009 19:16
• Well my temp light doesnt come on anymore. I JUST made a seperate thread about that. I searched for answers to my continueing battery light problem and saw this one so i figured i'd just re-post.
  
  My thoughts are:
  
  a solid battery light means the batt is below a certain V.
  a flickering battery light means the V regulator isn't regulating properly.
  
  correct?
• #12 by 8v-of-fury on 17 Mar, 2009 19:30
• i noticed that in this past winter my bat light would stay on after starting for 5-7 seconds.. or if i revved it immediately after a starting it would go away.. I wonder if the light actually has to do with what is coming from the alternator.. because I do believe it is one small wire on the back of the Alt that is what the bat light reads from. and if this is disconnected it will show solid light, or similar to incorrect voltage.. Hows your alternator? sure its not a problem with it? have you checked to see what the alt is producing while its actually running?
  
  just some thoughts.. i doubt I'm right lmao
  
  p.s did you let your friends idiot GF help you wire up anything? maybe she sabotaged your electrical like your door handle? lolol
• #13 by Smokey Eddy on 17 Mar, 2009 19:52
• Thanks Jer :roll:
  
  Yeah, i have a V meter i picked up for free    I'll check and see what the charging V is.
  
  That small wire coming out of it looksvery decrepid.