OD Lockout......Need HELP!!!!!!!!

[GMC-2002-Dmax]

Well I decided to mount my High Idle and OD lock out Switches in my pod with a RED LED for both.

I had previously temp. wired the high idle and did not have a switch that I liked, but I bought 2 from Radio Shack and put them in with the LED's with the 10k ohm resistor built in for both HI-IDLE and the OD lockout.

I had already had the reflash for the shift business so I knew that the OD-Lockout was activated.

Anyway I tried the Hi-Idle, no problem....LED lights, 2 clicks of the set and I am at 1200rpm. One click of the resume and 1800rpm.

Now the OD-Lockout :( :( . I warmed up the truck with my HI-Idle and took it out for a drive, I have not activated the switch yet. I waited for the shift into 5th gear and hit the switch, 2 seconds later I am in 4th smile.gif , I hit the switch off and it goes into 5th, BUT....> The LED stayed on, very faintly lit :eek: , I tried the OD-Lockout a dozen times and it works the way it should, I did not see the LED lit until I activated it the first time, now it is faintly lit when off :confused: :confused: .

Anyone have any idea where I should be looking??? I spent a lot of time and was real careful. I even checked to make sure that the LED was not picking up light from the gauges, it's not.

Could I have a defective LED??? per the instructions it said that pin C1-20 makes the ground when the switch is activated.
I will double check that I have not pinched the wire and it is making a ground, it seems like a weak ground to the LED???

HHHHEEEEEELLLLPPPPPPPPPPPP!!!!!!!!


GMC :(

[dmaxster]

if it was me....I would try to put a diode in series with your power wire or your ground....you maybe receiving a back feed and a diode will eliminate this....you can get them at radio shack too...they're like 1 or 2 bucks for two of them....there rated for on amp.....good luck....dmaxster
:D

[GMC-2002-Dmax]

dmaxster,

I used the LED w/ built in 10k ohm diode from Radio Shack.

Part Number for RED was 276-270. I also have a green one 276-271 that I did not use.

The Diode is built in so should I try and switch the leads on the diode to see if it makes a difference????

I assume red is (+) and black is (-) on the diode.

If I used 12V(+) for the red side and the C1-20 wire which is ground for the LED thru the TCM it should be right.

Maybe a bad diode????Maybe it matters which side if the LED the diode is on.????

I would like to see if someone else knows if it matters. It's a real pain to get at the diode and swap the leads.

Will it hurt anything to leave it the way it is?????

Thanks,

GMC

[Tinbender]

I did the ODLO using the same parts from Radio Shack that you used. I have the same problem, a very faint glow that can only be seen at night. I installed the ODLO just before we left for the sunshine in the south so I just kind of ignored it. After 7000 miles all seems well, works fine, but still has the glow. I'm sure it's getting some stay voltage back some how. Maybe a diode in the hot side would cure the problem. Then again the light is a diode. ??

Bob

[GMC-2002-Dmax]

Tinbender,

At least I can stop pulling my hair out. I can rule out a defective LED and a thanks for the info.

I will leave it as is and I will try a 10k ohm resistor inline on the hot side of the wire leading to the LED. If that does not solve the problem I will switch it to the C1-20 negative side of the LED.

Anyone know if it will hurt to add the 10k ohm resistor to both sides???

GMC

[mdrag]

GMC-2002-Dmax,

I also have a VERY faint glow in my ODLO LED - you almost have to look for it. I initially used the green Radio Shack LED w/resistor and then switched to a blue LED and added a resistor. I don't recall if the faint glow was present in the green RS LED...

My ODLO was installed in Oct/Nov 2002 and I have not noticed any problems.

[GMC-2002-Dmax]

Well I did some more checking,

I have a digital multi-meter and opened up the RS-green LED w/ built in 10k ohm diode.

This is what I found on anothet sight ...>http://jag-lovers.org/lumps/tech/basics/diode.htm

If you read it I checked my extra diode. When I apply red lead to red lead and black to black from the meter to the diode I get a high reading when set at 20k the reading id 19.80. When I go from red-meter to black on Led lead and black on meter to red on LED lead the reading stays on 1.

Does anyone know what is allowing current flow and what isn't based on those readings??

This is what it says on the link: When a voltage is applied in the reverse direction we say that the diode is reverse biased. When the diode is reverse biased, the potential barrier builds up across the junction and opposes current flow through the diode. The greater the applied reverse voltage, the larger the barrier. When reverse biased, only a very small leakage current flows. This leakage current is called the reverse saturation current

If you get the same reading, or close to the same for each of the tests, the diode is no good. You should get a big swing in the meter when you reverse the leads.

It will read very low one way, and very high the other. This indicates that it is passing current in one direction (low reading) and blocking it in the other (high reading).

The high reading for most all diodes should be above 1,000,000Ohms. ( 1 megohm)

The low, forward reading will in the 1-1000 Ohm range, depending on the
current rating of the diode (low Resistance allows for high I [current] ).


If you have a digital meter, there is no needle to swing.

You will get numerical readings. Same results apply.

So if I go by that then the Diode I have needs to be wired for 12v+ on the black side and the ground needs to be on the red side of the LED.

Any Suggestions????

GMC

[mdrag]

GMC-2002-Dmax

IIRC,the Radio Shack LED has a built in resistor and not a diode...

I understand that the resistor could be placed on either the positive OR negative leg of the LED.

If you figure this out, please post your findings. Good luck.

mdrag

[oyazi]

MHO there is much ado about all this. Keep in mind that LED is a diode in itself & functions as result of reverse bias/barrier junction. The lite emitted is a byproduct of reverse bias.

On mine, I experienced the same thing w/o a diode (other than the led itself) but I had a separate resistor ~ fact is, I used a variable resistor/rheostat to establish the threshhold/brightness level that I found comfortable/easy to see. Then replaced it w/a fixed resistor of the same value. A friend simply left his in the circuit. I would think in your case a slightly increase in resistance value would resolve your issue. Be aware that nominal tolerances are 20% and sometimes one must select among several resistors to get what they need. More precise resistors are avail however. The resistance should be such to limit the current to protect the LED from destruction/thermal runaway I wouldn't allow it to become an obsession tho ~ yeah, I know what that is. ;)

Finally, in that the led is really a diode itself, I fail to see value of adding yet another diode. . :confused:

[ 04-07-2003: Message edited by: oyazi ]</p>

[GMFAN70]

Understand that current thru your LED/resistor unit is switched on and off by a solid state switch(SSS)in the TCM. Current on, light. Current off, no light. But solid state switches are not perfect and can allow leakage current to flow even in the "OPEN" state. My LED is completely off in the off state, indicating that my TCM SSS is pretty good with very little leakage current. In your case it appears that your TCM SSS allows enough leakage current to keep your LED slightly energized in the "OPEN" state. Your only option is to add series resistance to reduce current flow. This will reduce brightness in both the on and off states. (Or try a new TCM ;)).

Good luck.
Frank

[Comet]

The other possibility is the ground on the battery supply (chassis) is at a different level than the TCM ground. This could result in a voltage diffenet between grounds and current flow will result.

Another fix may be to use a TCM power supply output line to supply the LED circuit. This would make the supply and ground part of the same "system".

Also, adding a 2nd 10K ohm resistor will just drop more current across the resistors and make the LED dimmer (if you will be able to see it lit at all).

[oyazi]

I'm thinking an additional resistance on the order of 180ohms to see just how much improvement in the ODLO 'off'/background glow and possible impact of the ODLO 'on' glow. Variable resistors are nice in situations like this. As I recall, the resistance required by my friend in his installation was significantly different from that of mine even tho we use the same components.

[ 04-07-2003: Message edited by: oyazi ]</p>

[GMC-2002-Dmax]

Oyazi,

Do you have an LED with a built in resistor?? Or do you have a LED with a seperate resistor.

The instructions said GM recommends a 10k ohm resistor. Does that mean 10000 ohms??? K meaning 1000???

If you did solve the glow when off what resistance in ohms was the right one to fix it.

I guess I should have did some more checking before I bought the LED's and the resistors.

It seems that several members are seeing the same results. Are we all using Radio Shack stuff????

Any help would be appreciated. At this point I do not mind the slight "GLOW", but it would be nice to have it off.

Thanks,

GMC ;)

[ndamico]

Oyazi you are correct. i left my variable resistors in place and my red ODLO has a faint glow when off. i believe i have it set at 850-900ohms. if i get rid of the "off" glow then the "on" glow isn't bright enough for me. i have actually come to like it as it illuminates the switch enough to just see it in the dark when i'm looking for it! :D

[oyazi]

No, didn't use Radio Shack stuff. Ndamico & I used led switches ~ and unfortunately I don't recall the source but they did required separate external resistor. Our resistance values were slightly different ~ again, unfortunately I failed to record the values BUT I seem to recall that both (HiSpeed Idle install and the ODLO install) required much less than the cited 10K.
I seem to recall mine were much lower in value than his or yours. Only my ODLO has background glow. Its only noticeable in my darkened garage. I should increase the resistance value but didn't notice it until I had encapulated it and tied everything down. If I recall right, I had settled on 970ohm ~ yes, one tenth of what the article suggested. 10K wouldn't glow at all in mine. I've plenty of brightness to spare so think I could increase it slightly w/o to much loss on the 'on'. Perhaps ndamico will come onboard w/specifics ~ If your 10K allows for max briteness, I think I would add a small resistor in series and see how it changes things. You might be able to wipe it out completely w/o affecting the 'on' briteness too much. (Note to self ~ start documenting this stuff) :(

[oyazi]

GMC-2002-Dmax ~ while sitting in my darkened garage trying to fathom out if my heated mirrors were indeed heating, it occurred to me; do we want to eliminate the background glow? Unlike the fast idle in which one is probably doing something outside of the truck and reaches in to switch it on, the ODLO is something used on the fly ~ day or nite when called for. With this faint glow ~ its easier to find/locate to activate in a darkened cockpit. There is no doubt when activate it is much much brighter. Naw, lets leave well enuff alone ;)

[carnutsx2]

Im going to go with the difference in voltage between the tcm and the body ground.How about using a transistor to switch the led or run a relay to make a clean break..... As far as the need to find the switch I have some parts on order so I can use the tow/haul button just like the 2003s. If all works out Ill post how I did it

[GMFAN70]

I used Radio Shack devices. The LED assembly was rated for 12 volts which means it included a series resistor to limit the current to a value appropriate for the LED. 10 K ohms and 12 volts yields 1.2 milliamps which sounds about right for this type LED. It also sounds about right for the current capability of the TCM solid state switch (SSS).

Be careful with the external load you put on the SSS connection. If you draw too much current you can destroy the SSS and lose that monitor function. It certainly can't handle an electromechanical relay. It can obviously handle safely 1.2 ma and maybe as much as 5 ma. Adding series resistance in the LED circuit will reduce the current so you can do that safely.

P.S. How do you insert the "Instant Graemlins"? All I get is colon and parenthesis.

[GMC-2002-Dmax]

To All,

Thanks for the reply's, I will be getting a variable resistor and will post some results. I talked to an electronics guru I know and he gave me a 300ohm resistor to try.

By the way, the LED's light so bright that evertime I take a picture all I see is red :eek: .

I think I am looking at the SUN!!!!!! :eek:

Anyway, I will try to get it done and post some new PICS.

GMC smile.gif

[ 04-08-2003: Message edited by: GMC-2002-Dmax ]</p>