Coolant glow plugs -effect on warmup

[Vince Waldon]

Love the trailer light tester for status... perfect for the job, and cheap!

 

[NarfBLAST]

Love the trailer light tester for status... perfect for the job, and cheap!

I know, eh, three LEDs already wired for 12V use, and readily available plugs and wires: I had planned on extending the wiring so that I could see the indicators while driving, but I don't think I will bother.

Now I know that the ECU uses only two relays to run the plugs but to keep things simple I used three relays and three lights so that way I don't have to care which plug is powered by which relay in the car. I didn't even bother labeling any wires from the car before I cut them.

 

[Vince Waldon]

I know, eh, three LEDs already wired for 12V use, and readily available plugs and wires

Princess Auto's finest??!

 

[NarfBLAST]

Princess Auto's finest??!

POWER FIST brand all the way!

 

[NarfBLAST]

I had a though while driving around today. The lights dimming could be partially due to engine glow plug afterglow happening at the same time that I am forcing the glow plugs on. I read somewhere that the programming is very careful not to run all seven glow plugs at the same time. I realized I could easily modify my circuit by adding another relay to cut power to the manual coolant glow plug circuit whenever the engine glow plugs are on! As an added bonus the LED on the dash would be OFF whenever the engine glow plugs are in "afterglow" mode, which is something I had been curious about anyway. Now you might say, "won't it be annoying having to wait for the led to come on before pushing the button" - no problem, the second switch is wired to "hold the button down" so I just have to flip the second switch up and the coolant glow plugs will come on as soon as the engine glow plugs shut off.

I went back to Princess Auto and picked up that extra relay today, my circuit is now complete! Details here: http://forums.tdiclub.com/showpost.php?p=4983956&postcount=318

 

[Vince Waldon]

The lights dimming could be partially due to engine glow plug afterglow happening at the same time that I am forcing the glow plugs on. I read somewhere that the programming is very careful not to run all seven glow plugs at the same time.

Yup, it's why the ECU monitors alternator output current via a DF connection, and why it can turn on 1, 2, or 3 coolant plugs at will.

15A X 4 engine plugs......60 amps
15A X 3 coolant plugs.....45 amps
blower fan.................. 10 amps?
DRLs or headlights.........10 amps?
charging a cold battery...10 amps?
.................................=======
..................................135 amps for a 120 amp alternator, never mind heated seats and a stereo thumpin' Justin Bieber.

 

[turbocharged798]

My 99.5 seems to run one glow plug at first, then run two after a few seconds, and then right when afterglow ends it fires up all 3.

 

[JB05]

Only one coolant GP is activated during the time that the engine GP's are ON. Once the engine glow plugs shut off, the single, middle coolant glow plug shuts off and the two outer ones are ON. Not sure about step 3, when all three are ON. I installed the coolant GP's on my auto equipped Golf. Two relays that I can turn on and off with an OFF-ON-ON-ON switch mounted on the dash above the stereo. I also have two blinking LED's directly connected to two of the coolant GP's.

 

[Digital Corpus]

Yup, it's why the ECU monitors alternator output current via a DF connection, and why it can turn on 1, 2, or 3 coolant plugs at will.

15A X 4 engine plugs......60 amps
15A X 3 coolant plugs.....45 amps
blower fan.................. 10 amps?
DRLs or headlights.........10 amps?
charging a cold battery...10 amps?
.................................=======
..................................135 amps for a 120 amp alternator, never mind heated seats and a stereo thumpin' Justin Bieber.

If memory serves, the A4's parameters are similar to the B4's: If the coolant is below a certain temps (escapes me at the moment) the engine glow plugs stay on as long as the engine RPMs are below 2500 RPM.

 

[jayb79]

I have had LEDs and switches on my coolant glow plugs for a few years now. There are only 2 relays that power all 3 glow plugs. All 3 plugs will only power up after the combustion plugs stop cycling after the engine gets to about 55-60f. The coolant plugs will stay on until the coolant temp gets to aprox 125f.

 

[FlyTDI Guy]

I have had LEDs and switches on my coolant glow plugs for a few years now. There are only 2 relays that power all 3 glow plugs. All 3 plugs will only power up after the combustion plugs stop cycling after the engine gets to about 55-60f. The coolant plugs will stay on until the coolant temp gets to aprox 125f.

Good stuff. Other than checking them to make sure they're good, didn't know the specifics of when and how many come on. I have the Bentley info and it spells out most of the details but... this fills in the gaps. Good info.

 

[1975 Kombi]

Is there an output test in VCDS to power the relays to check this??

 

[Vince Waldon]

No one's ever found one that I'm aware of... they just fake it out by unplugging the CTS. The trick is that the IAT also has to think it's cold too.