runningallday
Well-known member
My entire ownership of my 1999.5 mk4 jetta tdi (since I was 14 in 2004 lol, yes I still have the same car haha), I have struggled with cold starts. Mostly because I typically only take short trips, and when it's below zero, I don't think the battery recharges in that short period of time. I remember, anytime it was less than 0F, I would need a jump start maybe 50% of the time. Which was embarrassing.
So here I am, 20 years later, still driving the same car - perhaps I'm stubborn or maybe I'm a romantic at heart? lol. But anyway: I have finally found an easy solution to the low battery problem! I permanently installed a Noco Genius 5 amp charger on top of the subwoofer in my trunk and hooked it up to the same 4 gauge battery cables. Now it is effortless to plug in the cord dangling outside my trunk, and the charger remembers that I have an AGM battery and charges my battery in AGM mode.
I should also note: I have had a lot of issues over the years with glow plugs and the glow plug harness. I ended up replacing the whole thing with a homemade solution ~5 years ago, which has worked flawlessly since then. So I definitely recommend solving any glow plug issues as well as charging up the battery.
Back to the story: in order to really feel good about myself, I went out and started it the other morning when it was -17F. I initially had some trouble sliding the key in the ignition, it was basically frozen solid. (I have since lubed it with Dry Lock Lube, fixed now) On the 3rd try, it started! The idle probably took 30 seconds to even out but it did start!
The first two tries didn't work though - actually the starter solenoid disconnected, making a whirring noise (It is a crappy local parts store starter that I replaced while on a trip. I think I need to finally install the better Valeo starter I bought a while back, and also upgrade the cables to 1/0, literally have been meaning to do this for like 2 years lol). Who knows how cold it will start after implementing these modifications!!!
And finally: yes my jetta started in this freezing cold, but my blower did not work. And my wipers would not work. So I drove to Aldi's to test-drive it... and yeah driving in the coldest part of the winter without the blower is not fun and actually quite dangerous because my breath quickly fogged up and froze onto the windshield. Not to mention people kept honking at me (not sure if it's because I left the charger cord hanging out my trunk, or if my taillights weren't working? It was a short drive, and I was not brave enough nor warm enough to ask them in the middle of traffic.)
So I removed the glove box. Dismantled the blower. Didn't take long at all but it was freaking freezing cold. I checked the voltage to the blower plug (it had 14 volts) and assumed the blower was bad (even though I had replaced it just 2 years ago). After doing a lot of reading I was ready to order a new blower and new resistors - when I thought I should go ahead and confirm the blower was shot, by supplying it with 12 volts. The blower started spinning immediately. So I was very confused, and put it back in the car - it began working perfectly. What the hell?
This was about the time I started to realize: this is definitely one of those annoying intermittent electrical problems. The wipers not working should have been a dead giveaway. The issue was that they had randomly started working again and I thought maybe they were stuck to the windshield or something.
Some quick googling pointed me in the direction of "Relay 100", and after tearing apart the left side panels under the steering wheel (don't worry it only took 30 seconds since the screws have been gone for about 10 years) I confirmed I had a Relay 100 that I could replace. I will add this to my order of other maintenance items from RockAuto and swap it out for $7.
Years ago, when I was at college, I had relay 109 fail on me a few times, leaving me stranded, before I finally found the solution here and swapped out the relay. Not a good feeling when it happens, but sure am glad that we can easily resolve these issues by sharing experience.
TLDR: Charging your battery makes your car start faster; mk4 Jetta is probably one of the most fun cars to work on and modify; always confirm parts are broken before ordering new stuff; and my Relay 100 apparently begins failing at -17F? Lol another wonderful mk4 Jetta adventure!
P.S. the 100 Relay didn't smell burnt or anything... just like a crayon
So here I am, 20 years later, still driving the same car - perhaps I'm stubborn or maybe I'm a romantic at heart? lol. But anyway: I have finally found an easy solution to the low battery problem! I permanently installed a Noco Genius 5 amp charger on top of the subwoofer in my trunk and hooked it up to the same 4 gauge battery cables. Now it is effortless to plug in the cord dangling outside my trunk, and the charger remembers that I have an AGM battery and charges my battery in AGM mode.
I should also note: I have had a lot of issues over the years with glow plugs and the glow plug harness. I ended up replacing the whole thing with a homemade solution ~5 years ago, which has worked flawlessly since then. So I definitely recommend solving any glow plug issues as well as charging up the battery.
Back to the story: in order to really feel good about myself, I went out and started it the other morning when it was -17F. I initially had some trouble sliding the key in the ignition, it was basically frozen solid. (I have since lubed it with Dry Lock Lube, fixed now) On the 3rd try, it started! The idle probably took 30 seconds to even out but it did start!
The first two tries didn't work though - actually the starter solenoid disconnected, making a whirring noise (It is a crappy local parts store starter that I replaced while on a trip. I think I need to finally install the better Valeo starter I bought a while back, and also upgrade the cables to 1/0, literally have been meaning to do this for like 2 years lol). Who knows how cold it will start after implementing these modifications!!!
And finally: yes my jetta started in this freezing cold, but my blower did not work. And my wipers would not work. So I drove to Aldi's to test-drive it... and yeah driving in the coldest part of the winter without the blower is not fun and actually quite dangerous because my breath quickly fogged up and froze onto the windshield. Not to mention people kept honking at me (not sure if it's because I left the charger cord hanging out my trunk, or if my taillights weren't working? It was a short drive, and I was not brave enough nor warm enough to ask them in the middle of traffic.)
So I removed the glove box. Dismantled the blower. Didn't take long at all but it was freaking freezing cold. I checked the voltage to the blower plug (it had 14 volts) and assumed the blower was bad (even though I had replaced it just 2 years ago). After doing a lot of reading I was ready to order a new blower and new resistors - when I thought I should go ahead and confirm the blower was shot, by supplying it with 12 volts. The blower started spinning immediately. So I was very confused, and put it back in the car - it began working perfectly. What the hell?
This was about the time I started to realize: this is definitely one of those annoying intermittent electrical problems. The wipers not working should have been a dead giveaway. The issue was that they had randomly started working again and I thought maybe they were stuck to the windshield or something.
Some quick googling pointed me in the direction of "Relay 100", and after tearing apart the left side panels under the steering wheel (don't worry it only took 30 seconds since the screws have been gone for about 10 years) I confirmed I had a Relay 100 that I could replace. I will add this to my order of other maintenance items from RockAuto and swap it out for $7.
Years ago, when I was at college, I had relay 109 fail on me a few times, leaving me stranded, before I finally found the solution here and swapped out the relay. Not a good feeling when it happens, but sure am glad that we can easily resolve these issues by sharing experience.
TLDR: Charging your battery makes your car start faster; mk4 Jetta is probably one of the most fun cars to work on and modify; always confirm parts are broken before ordering new stuff; and my Relay 100 apparently begins failing at -17F? Lol another wonderful mk4 Jetta adventure!
P.S. the 100 Relay didn't smell burnt or anything... just like a crayon
