Flashing glow plug light, SEL and some observations

I found the flashing GP light to be my right brake light out. The left is disconnected due to damage from a hit and run I haven't had repaired.

CEL codes are po245, po672 and po674

the 245 is low volts wastegate solenoid A which I understand is most likely an N75 valve issue. I pulled the connector and everything looks clean so I plugged it in and pulled it a few times just to create a new connection if there was an issue.

The others are glow plug 2 and 4.

I cleared the codes and they have not returned in 30 min or so of run time with 3-4 short trip engine run cycles.

I first thought the flashing GP light was a significant issue with GP after I saw the GP codes, now believe them to be unrelated after seeing the massive list of what can flash the GP light.

The CEL has remained off and I have some questions about how the GP and CEL lights reset.

After changing the brake bulb, I pressed the brake pedal several time before and after turning the key on with no crank. After 20 seconds or so the GP light flashed. I thought, maybe there is more than one issue causing the GP. I started the engine, cycled the brake for the heck of it. I then toyed with the holding the brake pedal and stepping on the fuel pedal. It holds at 1200 rpm unless I let off the brake or go to zero fuel then add again. After 1-2 minute(s) of random messing with this looking for patterns, the GP light quit flashing and stayed off and has not come back. Why the 1-2 minute delay in reset?

The CEL light has not come back on. If the glow plug issues are still there, whey would the CEL not come back on after 20 seconds or so like it does on every start with code setting issues present?

I've noticed in the past when I reset the po245 boost related code, sometime it takes hours or days for it to reoccur. I will check for 16-20 ohms at the n75 terminals to see if it is good or bad. My guess is it is bad, but if it is, or if I have a vacuum or boost leak somewhere causing a problem I am curious whey it does not set a code fairly soon after running and driving it again?

If I get the glow plug codes again, late for whatever reason, instead of immediate, I will check them for resistance and replace bad or all as a group.

What is the with the fuel limit while holding the brake and why does it seem to go away allowing the engine to rev with seeming full fuel if I mess with the fuel pedal? Manual trans in this case.

Also, new tstat and G13 but this thing for a quite a while has taken a while to warm up even at 60-65 mph this time of year in 50-60 degree temps....not that cold. I run it for at least 5 min on the freeway after short trip to freeway before it's warm. I know why diesels are slower to warm than gasoline engines in general, it just seems a long time to get to 155 where the needle first sits on 190.

In my GP research I noticed manual trans cars have coolant glow plugs that are out of the normal loop. Are they likely still working at 280k miles or is there an indicator if they aren't or standard resistance (ohm) test? Should I mess with them if I don't routinely do stuff below freezing? Anyone test how they affect engine warm up? I don't know what the parameters are for the coolant GP, do they even engage above freezing or lower temps, if so does anyone know at what temp they stay off either at cold start or after running to help warm up, not sure if same or different temps.

Thanks

Vw TDIs are throtle by wire, meaning the fuel pedal sends an electrical signal to the car's computer (ECU).
As one of several safety measures due to the possible catastrofic results in case of a stuck pedal etc, the ECU will cut the revs if the brake pedal is pressed at the same time as the fuel pedal.
Another scenario is when the fuel pedal signal is lost, the ECU will increase the RPMs to around 1300 to allow the car to be driven albeit slowly and avoid being stranded.

If the Brake Switch is not fully closed the ECU does as Carlos_TJ stated. And, if the Clutch Switch is not fully closed, same thing.

The ECU monitors both brake light bulb circuits but not the one in the window. If both of the brake light bulbs are blown, the GP light will flash. And, there are at least a dozen things that can cause the GP light to flash... there is a list floating around in the various Threads.

The Coolant GPs are not monitored by the ECU. Their only function is to hasten warm-up. I'm not sure at what temp they are active. Just guessing, I'd say almost any temp activates the coolant GPs because their function is to assist with bringing the engine up to operating temp ... better emissions with fully warmed up engine!

Any knowledge of indication coolant glows are working short of grabbing them right after starting engine and see if any extra heat is noticed?
resitance from the lead to a ground? any known ranges?

I have driven more with a couple short hard pulls in 3rd and 4th gear, feels great, no CEL yet.

I just measured resistance on the N75 at 16.1-.2 ohm stable with body temp of 96* F. Its been in there since 2004 so I assume original. That's one end of the range, should I check again hotter or colder, such as tomorrow near sunrise when it will probably be at 50*? Seems like it's probably fine just that it's not 0 or infinite and within the 16-20 ohm range quoted around here and prob in the manual.

What is second guess for po245 low wastegate solenoid A voltage? Something else electrical, something on the wastegate end? Vacuum? Ive got all original vacuum/boost lines on this thing. No obvious breaks in them, but what to check first if that's likely place to look?

For whatever reason it's taking a long time to get any of those three codes back, one watstegate, two glow plug related. I did pull the harness off each GP and set back down 2-3 times to scrape them a bit, but no sign of corrosion. I know at least two GP have been changed cant recall if all have. If all haven't I assume 2 and 4 are the ones that weren't and they've lasted this long. The car has been in very temperate low altitude SoCal climate since 2004.

Is it uncommon to get GP related codes in error now and then? Are they the type of codes that will clear on their own after a number of start cycles or time if not consistent or will they hang in there until cleared regardless if the values are only occasionally out of range?

N75 now at 15.3 ohm with 59* body temp. That is lower than the 16-20 range Ive seen but not sure if related to solenoid A low voltage code PO245. At higher temps similar or even cooler than normal valve temps it's within range at 16.1 or so.

Several cycles and medium to high boost burst now with no CEL.

No CEL after several hundred miles now. was expecting the PO245 to come back as it has at least twice before. Anyone unplug and plug in pristine looking connectors/pins on these things and fixed 'issues' like this? Mileage seems to have improved, not sure if the computer alters timing etc with codes like this? I picked up several mpg.

Coolant GP's by themselves are not monitored by the ECU, But their two controlling relays are; I don't recall the specific DTC's off hand. The flange which they screw into gets very hot, and each one draws ~ 11 amps. There's an ancient write-up here that gives some insight to the coolant GP function; middle one on when the four engine GP's are on; two end ones on and middle one off for some time; and eventually all three. I do not know the duration.

Now I'm getting what feels like same limited fueling with no CEL. I'll check for codes shortly incase there's something wrong with the CEL function. Anyone ever get limp fueling with no CEL and no codes? This is my first. I guess all along CEL or not this is whatever fuel comes with no boost. It doesn't seem to smoke while down on power, just feels like about 1/3 of normal maximum output with right pedal to the metal.

Yes, it's not uncommon to get a limp mode condition *without* any CELs. There's only so much the ECU could monitor in 2002, and it was mostly paying attention to emissions-related systems.

yes, just checked no codes, after a hot re-start after limp, it ran like a race horse every time I goosed it, for a five min trip. Same as with CEL limp, after restart it was always fine for a while but with CEL off, once po245 code CEL hit, back to limp.

I unplugged and re-connectd the turbo involved N75 connector several times even though it looked pristine back in December. It seemed to get rid of my CEL and any limp....now limp with no CEL.....shaking head. This thing is trying at times, but what are odds its the turbo N75? I should prob changes, it's original 16 years old and 28x,xxx miles. I could swap it with the other next to it to check I guess first, may not be worth it to mess with it though. I did see some slightly out of range low ohm values across the terminal once, I think when warm, not when cold.

You say you have the original vacuum hoses on a 16 year old car. Just change them.
Have you checked the actuator on the turbo? Does it move freely?
Have you ruled out the other common causes of limp mode? It likely isn't electrical.

Put a vacuum pump on the turbo actuator so see if it holds vacuum.

flee said:

You say you have the original vacuum hoses on a 16 year old car. Just change them.
Have you checked the actuator on the turbo? Does it move freely?
Have you ruled out the other common causes of limp mode? It likely isn't electrical.

Click to expand...

Ha ha!

1. I have 18 years on a set (wife's car- I keep meaning to replace them);
2. Yes (took a couple of years of spirited driving to free up sticky vanes, but now boosts very well- more boost out of this car than any of my others);
3. I have zero problems (no limp mode).

Sorry, couldn't resist