Glow plug and CE lights

LukeWilson said:

That's how i have it wired and it does work fine, but as other people have said, there is some kind of voltage leak because the light doesn't fully go out.

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You may want to try putting a 330ohm resistor across the LED and running a diode in series with the LED + resistor. I believe the ECU "looks" for the 0.6 volt breakdown from the diode. That may also fix the leak as well.

You also should have a 400-600 ohm resistor in series as well to protect the LED if you already don't have one.

LukeWilson said:

That's how i have it wired and it does work fine, but as other people have said, there is some kind of voltage leak because the light doesn't fully go out.

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No LED use the small dash Bulb (incandesant)...No Led's used in 98..

The '97 passat cluster that went with the engine had all LED's in it. It's not really a problem, i am just curious as to why it does it.

Luke

LukeWilson said:

The '97 passat cluster that went with the engine had all LED's in it. It's not really a problem, i am just curious as to why it does it.

Luke

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sry After further review I do see Diodes in Use there..

sry I had Not read entire post either.


after reading a lil more

97 passat TDI
mal ind lite dash T28/26 to ECU 9 Vio/wht
glow lite T28/20 to ecu 48 blu/grn or Yell/blk

LukeWilson said:

The '97 passat cluster that went with the engine had all LED's in it. It's not really a problem, i am just curious as to why it does it.

Luke

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dam I had a Huge reply & went for a link & lost it..short story..
12v side of glow diode check this link

http://en.wikipedia.org/wiki/Capacitor

Use that to clean A/C-D/C to Glow LED..( inst cluster Had v-regs & caps built in to make it work,up to U to recreate that enviroment)

I have dash to ecu pins as well glow ind led T28/20 to ecu 48 (97passat 68 pin ECU)

recomend a 50v 0.1 MFD cap to + leg of glow LED that should remove any A/C signal from Host to glow circiut.

damit wish i hadnt lost my earlier reply ..BUT
I think i have basic's of the 2 pager i had typed in.

from what i saw this wknd ECU has continuos A/C applied to All controlled devices to monitor for trouble codes..( Glow lite able to produce Fault Code)

I completed my wiring & left out 12v to N75 & stored continuse code..(had 12v wire open CHIT & wrapped around it)

anyways monitoring n75 with a noide lamp showed 4-5v pulse steady..however while testing N75 with vag com noide went to full brite..hope that makes sense..

Wow thanks, next time i have the dash apart I'll have to add a capacitor and see if that fixes things up.

Thanks again,

Lucas

just wanted to bump this up in hopes of any new information....getting ready to complete my dash wiring with the LED's for CEL/Glow.... I've read goldguru's advice but not sure how to implement....any advice?

Re. glow plug and CEL lights

This is how it's working for me in an '84 Toyota pickup with a '97 1Z in it. For what it's worth... My instrument cluster and relay/fuse block info has come from here:
http://www.a2resource.com/electrical/CE2.html
and I've cross checked it with Mitchell Repair schematics from the guys down at the local Napa auto parts store (who I forever owe beer).

My truck doesn't run yet and y'all's does, so like I said... fwiw...

LukeWilson said this, which helped me approach this...

Glow plug light - I'm [thought I was] using a Napa Echlin LED (12V) that I cannot find listed online anywhere. TGA030 is the number on the box, and it's orange. No voltage or electrical specs listed anywhere . But, it works wired either way - my kind of wiring . G 2/5, pin 68/48, blu/grn. Then I found some grn/wht wire on the steering column that has 12V with the key in run, clipped on the quick clip, and got my glow plug light! I thus eliminated the 'glow plug wiring short to ground' or whatever that VAGCOM error is.

Gauge cluster MIL light is yel/wht and in harness G 1/09, going to 68/60. I haven't connected it to a 12V LED and power source yet only because I don't have the LED yet.

I have both the oil pressure wires and the oil temp sensor wires labeled, and the coolant temp and sensors, too. I'll post 'em later when not so tired.

thank for that cummins.... I have a stupid question....has anyone ever wired an incandescent bulb to the ECM's that used LED's in the cluster?....does it really fry the ecm?

jimbote said:

thank for that cummins.... I have a stupid question....has anyone ever wired an incandescent bulb to the ECM's that used LED's in the cluster?....does it really fry the ecm?

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It would probably throw a fault code "CEL short to ground" or somthing like that. I guess its possible it could fry it. LEDs do not draw near as much current as a regular bulb does.

Re incandescents vs LEDs, gauges

Good question jimbote. Anyone?

The LED is the way to go, I guess, as voltage can't backfeed into the ECM with LEDs. Nonetheless, I today learned that I was sold an LED that is actually an incandescent. It is the glow plug light I was so proud of yesterday. It is 12V. It has not fried the computer. It has eliminated my glow plug fault to ground error. Upon cutting the MIL light out of the harness, I got the same error, short to ground/whatever it said.

The prospect of frying the ECM is too high with the incand.s. I just ordered these.

As for gauges, I am a bit perplexed here. I will review e*clipse's and LukeWilson's threads to see what worked. I aim to put a gauge on the high pressure oil pressure sensor at the oil filter housing. I also want to tie in a coolant temp gauge, too, to the existing wiring. I guess I need to know resistance values to do this properly...? I'll measure voltage today.

On my Saturn TDI project, I discovered that the relay wasn't working for the glow plug circuit, so I deleted it in favor of a manual switch. I get a CEL after the first minute or so of running time, with VAG-COM showing a glow plug circuit fault. I haven't figured out yet how to get around this, it's been low on my project list.

cummins....when you had the incandescent installed did you get any afterglow?....I'm gonna try an incan in my cluster depending on your answer....I'm running both the glow and cel using the 3 volt reference via ecm fan control wire, but the glow and mil are just too dim in daylight

OK...i'm the guinea pig!!...im running my CEL and Glow lamp with incandescents nice and bright on my Y2K ecm...with ZERO afterglow....if it burns out the lamp drivers in the comp then ohh well

Finally have to get around to wiring up a CEL due to our new etest here. My white/blue wire did not appear to have the correct glow plug light signal on it, so I pulled apart the 120 pin connector. Turns out, my harness did not have pin 24 populated. A quick check of a spare 120 pin connector I had revealed it did have pin 24, so I popped the pin out and populated it on the Jeep. Fired up the output test and cycled the check engine light. Success! So even if an ALH harness doesn't have the wire, it still sends the signal to the pin.

Reddok said:

Finally have to get around to wiring up a CEL due to our new etest here. My white/blue wire did not appear to have the correct glow plug light signal on it, so I pulled apart the 120 pin connector. Turns out, my harness did not have pin 24 populated. A quick check of a spare 120 pin connector I had revealed it did have pin 24, so I popped the pin out and populated it on the Jeep. Fired up the output test and cycled the check engine light. Success! So even if an ALH harness doesn't have the wire, it still sends the signal to the pin.

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Awesome!...what car is your harness out of?...it's strange that VW does not have consistency on all the mkiv harness.... I've seen the beetles have some different wiring than the golf/jetta

The swap came from a 2002 Jetta. Not sure where my spare 121 pin came from. Earlier model I think.

So I've had my MIL lamp working - but inverted for the past 4 years. Trying to get around to fixing it. I've applied Jimbote/Alchemists fix with a transistor and it now functions as expected - except it's like my glow plug light - it glows dimly when its 'off'. Anyone come up with a working solution yet?

Reddok said:

So I've had my MIL lamp working - but inverted for the past 4 years. Trying to get around to fixing it. I've applied Jimbote/Alchemists fix with a transistor and it now functions as expected - except it's like my glow plug light - it glows dimly when its 'off'. Anyone come up with a working solution yet?

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use incandescents if it'll fit where your LED's are ... been running mine like this for six years no issues... even had a cel for several weeks at a time because i was too lazy to change out glow plugs

All surface mount LEDs in my cluster. I guess I have to figure out if the VW ECU is doing something for bulb-out detection that causes this, or if it's just a transistor biasing issue.

Reddok said:

All surface mount LEDs in my cluster. I guess I have to figure out if the VW ECU is doing something for bulb-out detection that causes this, or if it's just a transistor biasing issue.

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i read somewhere on the forums it's a bulb out detection current ... anyway
to defeat that ?

Use a zener diode inline? That possibly could work if the voltage is low enough where the zener can block it and let the current flow when the MIL is "on".

Uggh, I just realized that I used Jimbotes original wiring diagram - it was hard to tell which was which due to the Photobucket 3rd party blocking. Because the resistor was connected after the LED, it caused it to glow. Wired correctly and it functions as expected. Glowplug light is still glowing dimly - must be something different in the way that ECU output works (it is normally grounded when the light is supposed to be on - unlike the MIL).

Reddok said:

Uggh, I just realized that I used Jimbotes original wiring diagram - it was hard to tell which was which due to the Photobucket 3rd party blocking. Because the resistor was connected after the LED, it caused it to glow. Wired correctly and it functions as expected. Glowplug light is still glowing dimly - must be something different in the way that ECU output works (it is normally grounded when the light is supposed to be on - unlike the MIL).

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the MIL would glow dim too if you didn't have the transistor circuit in place

My MIL was on bright constantly without the transistor circuit in place. The ECU grounds the pin when the MIL light is off and goes open when the light is commanded on. This is the opposite operation of the GP light. Anyway, it's functioning properly now - they brought up the fact that it was on at my last emissions test so I wanted to make sure they had nothing to complain about this time. Hope it still passes the OBD test.

Reddok said:

My MIL was on bright constantly without the transistor circuit in place. The ECU grounds the pin when the MIL light is off and goes open when the light is commanded on. This is the opposite operation of the GP light. Anyway, it's functioning properly now - they brought up the fact that it was on at my last emissions test so I wanted to make sure they had nothing to complain about this time. Hope it still passes the OBD test.

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yep, as was mine until i applied alchemist's fix ... but before the fix, in the brief period between key on and starting, it would still dimly glow with the LED

Well, it passed its emissions test! Check engine light came on while I was driving to the test. Then it glowed dimly. Then it flickered. Then back to glowing dimly. No rhyme or reason for it's behavior. And no codes stored. Must be some stray voltage somewhere.

Interesting thread........I swapped an ALH in to a 2000 Audi TT earlier in the year. The car runs great but the cluster always shows a bulb out/low windshield washer fluid. My donor car was a 2002 Golf with the ECM and harness.

I'll have to check pin 24 on the engine harness and maybe wire it up if it's missing. That might clear up my bulb out/washer fluid light on the cluster.

Eric

The issue is the ECU is just giving a signal [switched ground] for turning on a LED and not providing the circuit to drive a LED.

When the ECU wants the light to come on, it supplies a ground. When the ECU wants the light off, it no longer supplies a ground and the circuit is floating and this float is what causes a LED to glow dimly as the circuit is in between 0V and 12V as you are supplying the other side of the LED with 12V.

The solution to the dimly lit LED issue is to use a resistor in parallel with the LED to act as a pull up resistor (along with the LED used to sync current for the LED itself). So 2K to 10K is all that is needed to cause the dimly lit LED to go totally out when it is off.

If you want to run a bulb with any current, a MOSFET is going to be needed as I wouldn't trust running current of any sort thru the ECU.

If anyone is interested, I a nice small box that will control up to 5W bulbs if need be and there will be no dimly lit LED either.

Hasenwerk said:

The issue is the ECU is just giving a signal [switched ground] for turning on a LED and not providing the circuit to drive a LED.

When the ECU wants the light to come on, it supplies a ground. When the ECU wants the light off, it no longer supplies a ground and the circuit is floating and this float is what causes a LED to glow dimly as the circuit is in between 0V and 12V as you are supplying the other side of the LED with 12V.

The solution to the dimly lit LED issue is to use a resistor in parallel with the LED to act as a pull up resistor (along with the LED used to sync current for the LED itself). So 2K to 10K is all that is needed to cause the dimly lit LED to go totally out when it is off.

If you want to run a bulb with any current, a MOSFET is going to be needed as I wouldn't trust running current of any sort thru the ECU.

If anyone is interested, I a nice small box that will control up to 5W bulbs if need be and there will be no dimly lit LED either.

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i have to disagree about using incandescents... been running stock toyota cluster incans for almost six years no issues ... perhaps these circuits are meant to run inandescent bulbs for applications other than automotive...remember they are not part of the mkiv stock warning lamp system but seem to be vestiges or intended for use in other applications ... the ecm's even have a tach output that's not utilized in the 121 pin cars ... i am using a pnp transistor circuit correct my CEL operation so that isolates the bulb "current" but i don't feel it's necessary to protect the ecm