clbooth71
New member
Lengthy post, but has some lessons learned documented that may be useful for other novices such as myself (and I won’t mind if you experts laugh at my stupidity as you’d be justified).
How NOT to learn about the starting circuitry of your VW TDI (and autos in general):
Initial problem:
Slow starting after over night (temps around 50F) but started fine after sitting for a few minutes up to 2-3 hours later.
Then one day, it wouldn’t start hot but it started with a jump to get me home.
Next morning – wouldn’t start, not even with a jump. Starter solenoid would engage, but starter wouldn’t turn over.
Cleaned battery terminal and cables, no change.
Replaced battery, no change.
Cleaned battery cable at starter, no change.
Replaced starter, no change.
Thought that maybe rebuilt starter I got may have been defective or possibly for a gas engine, so returned it for a 10% restocking fee and ordered one from a local automotive shop that specializes in European imports. Put it in – no change.
Suspecting starter wasn’t getting enough juice due to electrical problem somewhere else draining/shorting battery, removed all fuses and relays (this is when they got scrambled per previous post) and ripped out 3rd party (Ultra Start) security system/remote start.
Bought a Haynes service manual from PepBoys in a sealed wrapper. Didn’t have what I needed.
Broke down and bought a Bentley service manual.
With aid of users on this site, vwvortex, the Bentley manual, and searching the internet for the part numbers on the relays to figure out what they are generally used for, I believe that I got them all back on the proper locations – not necessarily where they were previously though… (so maybe not).
Tried to start it after all relays and fuses were reinstalled and nothing – not even the starter solenoid would engage. Found that when turning the key to the start position, the battery voltage would drop to zero indicating an apparent short. Back to the relay and fuse removal strategy. Found the source of the voltage drawdown at relay position 12 – Glow plug relay. Further investigation found that per the schematics there’s supposed to be no connection at terminal position 8, but the relay panel had 8 wired to ground and terminal 2 went to the line 30 which if I recall correctly has +12v when the key is in the on position was shorting straight to ground via the relay's terminal 8. I bent terminal 8 over on the relay and plugged it back in. The short was gone, but the starter solenoid would still not engage but the security control module was making odd noises. I ran a wire from battery to starter solenoid and confirmed that it would engage that way.
Back to the forums and the wiring diagrams to learn about the security control module. Based on info in the forums, I tried to bypass the security module without success. Based on studying the Bentley service manual, completely disconnected the security module and I ran a 10awg wire (probably could have done with 12 or 14 awg – oh well) from pin 50 on the ignition switch (red/black wire on my 98 Jetta) to pin 6 on the 6 pin connector cable for the security system (red/black wire). Starter solenoid now engaged when trying to start and starter would turn what sounded to me like one revolution (~1 seconds) then stops.
Removed the glow plugs to make it easier for the starter to turn. Starter turns with the key for 5 seconds no problem. Put the glow plugs back.
Disconnected cable from battery at starter. Battery voltage only drops a couple of volts.
It finally dawned on me to try to push start it to make sure it would at least run. I was able to start it by push starting it. I let it idle for 30-45 minutes, then turned it off and tried to start it again. There was not enough juice in the battery to light the indicator lights much less engage the starter solenoid. I connected the battery charger/booster and set it for 120 amps – still no go.
Disconnected the ground battery cable, connected the charger/boost/jump system to the ground battery cable and positive cable – still only turns over for only a second before stopping.
Voltage across pos and neg drops to zero when trying to start.
Got to thinking that maybe the battery charger/booster/jumper was not supplying enough current to get the job done. So, I did some math. The extension cable I was using to supply power to the battery charger had a 10 AMP breaker built in and it wasn’t popping (once I bent over pin 8 on the glow plug relay).
Doing the math:
Input: 120v x 10 amp = 1200 watts.
Output: 1200watts/12 volts = 100 amps - not enough to turn over the starter with glow plugs installed.
Sooo… I decided that the new battery was junk – insufficient from day 1. Based on the forums here, I decided to try to get an Optima red top and found a local parts store that carried them. Replaced it today and VOLIA!
Now that I know the battery was junk all along and the charging unit was insufficient, I figure I’ll revisit a few things such as the security module to see if it was not enabling terminal 6 because there was insufficient current from the battery, or if it was already dead and the previous owners installed a 3rd party unit rather than replacing this one. I figure I’ll also go back and revisit that glow plug relay that I thought was shorting out to see if maybe it is wired correctly and was just trying to draw a huge amount of current to heat the glow plugs from a weak battery causing the voltage to drop to zero. Additionally, the central locking system, radio, windshield wipers, and heat/ac fan have all quit working, so I need to look into the fuses and relays for those items now (I was already having problems with the wiper/blower relay, but not the locks and radio. The tac is acting kind of screwy when the engine isn’t running, but seems to work when the engine is running and the rest of the dash/console appears to be in operating order.
Lessons learned the hard way:
FIRST: clean (with file, sandpaper or other abrasive) the battery cables and associated contact points at the battery, starter, and frame
SECOND: Take the battery somewhere and have it tested for output current
THIRD: Buy a quality battery to start with if you need to buy a battery
FORTH: If you are using an external power source to test with, make sure it’s able to supply enough current to get the job done.
Cost of my fiasco documented above:
New junky battery (should have searched and read the forums first): $36
Restock fee for starter #1 that I couldn’t get working: $20
Starter #2: $210
Haynes manual: $20
Bentley manual: $90
New Optima battery: $140
Gas to run back and forth to parts stores & etc: $30+
Bottom line:
Cost of lessons learned the hard (and expensive) way: $406
Cost of quality battery to fix the problem: $140
Time with father working on and cursing at car then going out for drinks after as well as learning how to be a one vehicle family of 7 for over a month – priceless.
(The real kicker is that I hadn’t cleaned the battery cables at the starter or frame before buying the first junky battery and I gave them my old as a core, so I’ll never know if I even needed a new battery
)
How NOT to learn about the starting circuitry of your VW TDI (and autos in general):
Initial problem:
Slow starting after over night (temps around 50F) but started fine after sitting for a few minutes up to 2-3 hours later.
Then one day, it wouldn’t start hot but it started with a jump to get me home.
Next morning – wouldn’t start, not even with a jump. Starter solenoid would engage, but starter wouldn’t turn over.
Cleaned battery terminal and cables, no change.
Replaced battery, no change.
Cleaned battery cable at starter, no change.
Replaced starter, no change.
Thought that maybe rebuilt starter I got may have been defective or possibly for a gas engine, so returned it for a 10% restocking fee and ordered one from a local automotive shop that specializes in European imports. Put it in – no change.
Suspecting starter wasn’t getting enough juice due to electrical problem somewhere else draining/shorting battery, removed all fuses and relays (this is when they got scrambled per previous post) and ripped out 3rd party (Ultra Start) security system/remote start.
Bought a Haynes service manual from PepBoys in a sealed wrapper. Didn’t have what I needed.
Broke down and bought a Bentley service manual.
With aid of users on this site, vwvortex, the Bentley manual, and searching the internet for the part numbers on the relays to figure out what they are generally used for, I believe that I got them all back on the proper locations – not necessarily where they were previously though… (so maybe not).
Tried to start it after all relays and fuses were reinstalled and nothing – not even the starter solenoid would engage. Found that when turning the key to the start position, the battery voltage would drop to zero indicating an apparent short. Back to the relay and fuse removal strategy. Found the source of the voltage drawdown at relay position 12 – Glow plug relay. Further investigation found that per the schematics there’s supposed to be no connection at terminal position 8, but the relay panel had 8 wired to ground and terminal 2 went to the line 30 which if I recall correctly has +12v when the key is in the on position was shorting straight to ground via the relay's terminal 8. I bent terminal 8 over on the relay and plugged it back in. The short was gone, but the starter solenoid would still not engage but the security control module was making odd noises. I ran a wire from battery to starter solenoid and confirmed that it would engage that way.
Back to the forums and the wiring diagrams to learn about the security control module. Based on info in the forums, I tried to bypass the security module without success. Based on studying the Bentley service manual, completely disconnected the security module and I ran a 10awg wire (probably could have done with 12 or 14 awg – oh well) from pin 50 on the ignition switch (red/black wire on my 98 Jetta) to pin 6 on the 6 pin connector cable for the security system (red/black wire). Starter solenoid now engaged when trying to start and starter would turn what sounded to me like one revolution (~1 seconds) then stops.
Removed the glow plugs to make it easier for the starter to turn. Starter turns with the key for 5 seconds no problem. Put the glow plugs back.
Disconnected cable from battery at starter. Battery voltage only drops a couple of volts.
It finally dawned on me to try to push start it to make sure it would at least run. I was able to start it by push starting it. I let it idle for 30-45 minutes, then turned it off and tried to start it again. There was not enough juice in the battery to light the indicator lights much less engage the starter solenoid. I connected the battery charger/booster and set it for 120 amps – still no go.
Disconnected the ground battery cable, connected the charger/boost/jump system to the ground battery cable and positive cable – still only turns over for only a second before stopping.
Voltage across pos and neg drops to zero when trying to start.
Got to thinking that maybe the battery charger/booster/jumper was not supplying enough current to get the job done. So, I did some math. The extension cable I was using to supply power to the battery charger had a 10 AMP breaker built in and it wasn’t popping (once I bent over pin 8 on the glow plug relay).
Doing the math:
Input: 120v x 10 amp = 1200 watts.
Output: 1200watts/12 volts = 100 amps - not enough to turn over the starter with glow plugs installed.
Sooo… I decided that the new battery was junk – insufficient from day 1. Based on the forums here, I decided to try to get an Optima red top and found a local parts store that carried them. Replaced it today and VOLIA!
Now that I know the battery was junk all along and the charging unit was insufficient, I figure I’ll revisit a few things such as the security module to see if it was not enabling terminal 6 because there was insufficient current from the battery, or if it was already dead and the previous owners installed a 3rd party unit rather than replacing this one. I figure I’ll also go back and revisit that glow plug relay that I thought was shorting out to see if maybe it is wired correctly and was just trying to draw a huge amount of current to heat the glow plugs from a weak battery causing the voltage to drop to zero. Additionally, the central locking system, radio, windshield wipers, and heat/ac fan have all quit working, so I need to look into the fuses and relays for those items now (I was already having problems with the wiper/blower relay, but not the locks and radio. The tac is acting kind of screwy when the engine isn’t running, but seems to work when the engine is running and the rest of the dash/console appears to be in operating order.
Lessons learned the hard way:
FIRST: clean (with file, sandpaper or other abrasive) the battery cables and associated contact points at the battery, starter, and frame
SECOND: Take the battery somewhere and have it tested for output current
THIRD: Buy a quality battery to start with if you need to buy a battery
FORTH: If you are using an external power source to test with, make sure it’s able to supply enough current to get the job done.
Cost of my fiasco documented above:
New junky battery (should have searched and read the forums first): $36
Restock fee for starter #1 that I couldn’t get working: $20
Starter #2: $210
Haynes manual: $20
Bentley manual: $90
New Optima battery: $140
Gas to run back and forth to parts stores & etc: $30+
Bottom line:
Cost of lessons learned the hard (and expensive) way: $406
Cost of quality battery to fix the problem: $140
Time with father working on and cursing at car then going out for drinks after as well as learning how to be a one vehicle family of 7 for over a month – priceless.
(The real kicker is that I hadn’t cleaned the battery cables at the starter or frame before buying the first junky battery and I gave them my old as a core, so I’ll never know if I even needed a new battery
)