The "Alchemist's CEL MIL Functionality Fix" !!!

jimbote

jimbote

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Swappers rejoice!!....now you are no longer enslaved to using the VW cluster in your swaps!! ....using pin 24 white/blue as a CEL output can now be fully functional... here's the thread link.... http://forums.tdiclub.com/showthread.php?t=352982 ...happy swappin! :D ...yeah I get excited about these things:rolleyes: ....again thanks to Paul (Alchemist) for coming up with the circuit solution, you da' man!! EDIT!!! just wanted to add that this mod is NOT required on older 68 and 80 pin ecm's as the CEL output can be connected straight to a bulb and works great! ;)
 
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greengeeker

greengeeker

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I'm definitely excited about this and all your other wiring work arounds. Do you think you can snap a picture of your circuit? TIA
 
jimbote

jimbote

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I'll make another in the morning for a spare and snap some pics....basically you end up with four wires...one going to 12v one to ground one to the ecm pin 24 and the other to bulb....
 
Danielg42

Danielg42

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Man! I was thinking I'd just hook up my pin 24 to the Toyota cluster light and everything would be gorgeous lol.
I'd love to see the circutry in more detail.

The more I work on my swap, the more I realize how little I know lol.
 
Danielg42

Danielg42

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So did you end up running your own wiring/bulb into the toyota cluster, or did you tap into the cluster wiring?
If you tapped into the cluster wiring, how did you manage to interrupt the ground there?
 
jimbote

jimbote

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spiral arm, milky way (aka central NC)
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Tacoma 4x4 converted to TDI
Danielg42 said:
So did you end up running your own wiring/bulb into the toyota cluster, or did you tap into the cluster wiring?
If you tapped into the cluster wiring, how did you manage to interrupt the ground there?
Click to expand...
I just cut the ground (signal) wire going to the CEL @ the cluster and patched the circuit in there...
 
jimbote

jimbote

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spiral arm, milky way (aka central NC)
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Tacoma 4x4 converted to TDI
Some pics....


Corrected diagram


Breadboard with components arranged


Assembled


Another assembled view


Transistor diagram


Heat shrunk package ;)

Brown=Emitter to ground
Purple=Base to ECM output @ cluster
Black/Blue= resistor to 12 volts
Red/black= collector to ECM side of bulb ....

basically once the components are assembled you will cut the wire coming from the ecm to the cluster and patch this in:
*attach the base to the ECM CEL output
*the collector to the ECM side of the bulb
*the emitter to ground
*the free end of the resistor to 12v (other side will be tied to "base") ..... wires colors are your choice, I just listed the colors here for clarity and because that's what I had on hand....good luck and have fun with the magic smoke!! ;)
 
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jimbote

jimbote

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spiral arm, milky way (aka central NC)
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Alchemist said:
Nice neat package you have there. Three gold stars for you.
I don't know what may have happened to the original drawing, but here is where it is hiding now. http://pics.tdiclub.com/showphoto.php?photo=88395&title=lamp-driver&cat=all

Paul
Click to expand...
Thanks for the compliment :eek: and reposting the link!... the installed circuit in my truck looks like part of the factory cluster harness...no "project boxes" hanging from the wiring ;)...now if I can just figure out a way to eliminate that dakota digital thingie :D
 
VeeDubTDI

VeeDubTDI

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edited to add "MIL" to the title for searching :)

(newbies, this stands for Malfunction Indicator Light)
 
C

calbertson

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rural Missouri
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96 cherokee tdi
Thanks for this! I'm currently swapping an alh into a 96 cherokee and is wired similar to the Tacoma so this was a huge help.

Being from the middle of nowhere I had to order the transistor and resistor.

For those interested I used

digikey.com
Transistor p/n PN2222AFS-ND
Resistor p/n 6.8KH-ND

Total cost before shipping 37 cents.
 
C

CrAzYDr1veR

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Portugal
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MK1 Rabbit
hi does anybody have the drawings? i would like to use this for my oil pressure light, currently using a small relay. tks.
 
A

Alchemist

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They're back.

In case one circuit is not enough to handle all possibilities, here are two.

This one will cause the lamp to light when the ECU does not ground its output, and turn the lamp off when the ECU does ground its output. This will work where the lamp is opposite of what it should be i.e. on when it should be off.

The unmarked resistor should be 6.8K Ohms.



This one will cause the lamp to light when the ECU sends a + signal, and turn the lamp off when the ECU does not send a +V. The lamp will follow the ECU output directly, but the ECU will not have to supply the lamp current. It could also be used to isolate a 5V ECU pin from the 12V vehicle circuits.

 
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Hasenwerk

Hasenwerk

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Alchemist said:
They're back.

In case one circuit is not enough to handle all possibilities, here are two.

This one will cause the lamp to light when the ECU does not ground its output, and turn the lamp off when the ECU does ground its output. This will work where the lamp is opposite of what it should be i.e. on when it should be off.



This one will cause the lamp to light when the ECU sends a + signal, and turn the lamp off when the ECU does not send a +V. The lamp will follow the ECU output directly, but the ECU will not have to supply the lamp current. It could also be used to isolate a 5V ECU pin from the 12V vehicle circuits.

Click to expand...

In the 2nd example, the ECU doesn't send 12V to the circuit when it wants the light off, it only puts the circuit into a floating state at that moment - so not ground and not 12V - which can cause LEDs to glow when off.

I personally use an N-Channel MOSFET with a pull-up resistor.

G - Connect to ECU K29 or K83
D - Connect to Light / LED
S - Ground with a 4.7K to 10K resistor to 12V

Inside the ECU is a MOSFET as well, just that Bosch didn't use a pull-up resistor and they don't directly drive a light with it, so it is best practice to use an external MOSFET to handle the current. Some people have said "no problem" with using the ECU to sink 4 or 5W, but why risk it when that was never the design intent of the ECU to begin with.
 
jimbote

jimbote

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hasen, this circuit isolates the ecm from the CEL bulb current so your post above is largely irrelevant...again on my swap, the GLOW lamp is a small incandescent running directly off the ecm and has been for nearly seven years and 120k + miles.... it's my daily driver, so i think it's safe to say that it won't damage the circuit... that being said i have a question for you since you seem to have some special knowledge about these ecm's ... these outputs, CEL, Glow, and tach, that myself and others have identified and are using, are dead end circuits in the 121 pin harness, meaning they are not used for CEL, glow, tach in the mkiv platform .... so my question is, how do you know they are incapable or unsafe of supportiing small incandescents ? i do understand the stock mkiv cluster uses led's, however it does NOT use these outputs (CEL, glow) for those functions, it uses CAN or K-line (honestly not sure which).... so if you have special insight please enlighten those of us who are successfully using these outputs as to their intended purpose, and why you believe using a small incandescent is a bad idea... also the bulb i'm using is around 1.5w not "4 or 5"
 
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Hasenwerk

Hasenwerk

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jimbote said:
hasen, this circuit isolates the ecm from the CEL bulb current so your post above is largely irrelevant...again on my swap, the GLOW lamp is a small incandescent running directly off the ecm and has been for nearly seven years and 120k + miles.... it's my daily driver, so i think it's safe to say that it won't damage the circuit... that being said i have a question for you since you seem to have some special knowledge about these ecm's ... these outputs, CEL, Glow, and tach, that myself and others have identified and are using, are dead end circuits in the 121 pin harness, meaning they are not used for CEL, glow, tach in the mkiv platform .... so my question is, how do you know they are incapable or unsafe of supportiing small incandescents ? i do understand the stock mkiv cluster uses led's, however it does NOT use these outputs (CEL, glow) for those functions, it uses CAN or K-line (honestly not sure which).... so if you have special insight please enlighten those of us who are successfully using these outputs as to their intended purpose, and why you believe using a small incandescent is a bad idea... also the bulb i'm using is around 1.5w not "4 or 5"
Click to expand...
It's OK - you do what you want to do, I will do it my way. How exactly is isolating the ECU, the most important item of your whole TDI, a bad thing? No doubt you can run a few Watts thru the ECU and you can do it for years. I would rather not do that and if I recommend something to someone else, I would recommend the least harmful way of doing it. Unless you KNOW the ECU can sync some current, why risk it? Even you said it " i think it's safe to say that it won't damage the circuit" - you *THINK*??? but, unless I KNOW, I am going to treat it as though it can not / should not. MOSFET costs under a buck, so this is splitting hairs at this point and just another way of doing what can be done many ways. Transistor, FET, relay . . .

MK4 ECUs and later sends this instrument pod information over CAN not K.
 
jimbote

jimbote

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spiral arm, milky way (aka central NC)
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this thread is about the CEL and a circuit to flip the on/off ... this circuit, designed by alchemist, essentially isolates the ecm from the bulbs current, is that not correct ? i will do it my way David, and have for many 1,000's of cycles over almost seven years... in my book that's a successful and long lasting solution ... maybe the real problem is that i'm not selling anything ? this is FREE info on a public forum... i'm just trying to help people out with their swaps by being a willing guinea pig ;)
 
Hasenwerk

Hasenwerk

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jimbote said:
this thread is about the CEL and a circuit to flip the on/off ... this circuit, designed by alchemist, essentially isolates the ecm from the bulbs current, is that not correct ? i will do it my way David, and have for many 1,000's of cycles over almost seven years... in my book that's a successful and long lasting solution ... maybe the real problem is that i'm not selling anything ? this is FREE info on a public forum... i'm just trying to help people out with their swaps by being a willing guinea pig ;)
Click to expand...
Jimbote, what's your problem here? I am simply providing my solution and my ideas to the forum. If you think this is a personal attack against you, then you are sadly mistaken my friend as it is not. If you suggesting I am trying to sell something or perhaps pushing my wares here in this thread then again, you are mistaken. If what you are doing works for you then FANTASTIC and good on you - I believe you 100% and I am sure others can do it and not have issues too. I simply stated MY view on the subject and I don't think anything came across as an "attack" on you - if it did, I am sorry, but you need to realize that this is flat, emotionless digital communication and that I am not yelling at or scolding you in any way. If you read emotion into this, then again, not my intention. I am simply stating my opinion and what I do with my items, same as you. No harm, no foul and there is no need for anyone to take anything that I say personally.

Done.
 
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