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What ticks the Lamp control Module?

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Old 03-31-2005, 02:08 PM
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Default What ticks the Lamp control Module?

Does anyone know how much ohms or resistance the LCM has to see before it thinks the light is blown? Or does it just have to have continuaty (sp?). I'm thinkin of maybe hookin it up to a relay instead of actually to the light.. hee hee.. don't ask why..
Old 03-31-2005, 03:37 PM
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Default Re: What ticks the Lamp control Module?

Originally Posted by Drifter420
Does anyone know how much ohms or resistance the LCM has to see before it thinks the light is blown? Or does it just have to have continuaty (sp?).
From what I read of it in the FSM, I think of it as monitoring current flow on each lighting circuit (or _branch_ of the lighting circuit; although one fuse protects the running lights in general, the Adaptive Lamp Monitor module monitors different branches of it with different bulb groups in each). It compares what it'* measuring now (in amps, I guess) with what it measured during the last driving session, or maybe an average of some number of previous sessions, and if it doesn't see as much flow as it did last time, it flags a warning that a bulb is out.

So I don't think it would (or could) be measuring resistance -- for one thing, it doesn't warn of a blown bulb unless or until that circuit activates. Even though the power is coming from upstream of the ALM; the path from the ALM to ground through the bulbs is always there, so if it was measuring resistance, it wouldn't need to wait for you to turn on the lights before telling you that a bulb was out.

As for continuity, that will always be present as long as at least one bulb in the circuit is good, and yet the ALM can successfully monitor circuits having upwards of ten bulbs all in parallel, so I would say it'* measuring current flow, and comparing it to a stored history for each circuit.
Old 03-31-2005, 04:21 PM
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So it'* based on amps.. for each bulb.. so that means I will have to wire both headlights and hi beams to the 2 relays.. and possibly even a resistor just so LCM won't chime in thinkin of a blown bulb.. :? wasted energy for heat.. sniff sniff..

so now I have to find out how much amp draw it will read.. but if it'* based on something that was stored.. if I unplugged the battery overnight.. would it clear it so that with the minimal draw.. the LCM would think it'* ok?
Old 03-31-2005, 04:49 PM
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Originally Posted by Drifter420
so now I have to find out how much amp draw it will read.. but if it'* based on something that was stored.. if I unplugged the battery overnight.. would it clear it so that with the minimal draw.. the LCM would think it'* ok?
You'll erase everything if you yank the battery, including your ECM self-learning adjustments for the engine; you sure you really want to do that?

Anyhow, the lamp monitor will adjust itself over time to whatever the, um, current current draw is, if you get what I mean. That is, it doesn't have pre-programmed "right answers" for each circuit; it just watches the circuit behavior, looking for a sudden unexplained drop in current flow compared to... let'* call it "recent history" for that circuit.

I think you're going to need to do your own trial-and-error here. Let us know how it goes.
Old 03-31-2005, 05:27 PM
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Yea.. I guess I will have to pull the battery out and have the engine re-learn and see if that helps with LCM when I get to it.. I don't mind a re-learn as it'* finally gettin warm again.. and might as well let it re-learn spring summer mode.. lmao.. I"ll keep you guys updated.
Old 07-14-2005, 12:52 PM
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Default how'd it turn out?

this may be a little late, you might have already found out if it works or not. if it did work, let us know. i would also like to say that i installed HID headlights in my '89 bonneville with the adaptive lamp monitor. they have a separate ballast/starter, i hooked them up to the headlight wires and the monitor never came on to tell me i had a bad bulb. BUT then i had a bulb go bad on me, and the adaptive lamp monitor kicked in and told me i had a bad headlight... which i did. it'* smarter than i thought!
Old 07-14-2005, 01:27 PM
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You guys are talking two different system I think.

97 vs 89 should be pretty different and GM may have changed the way the system monitors the lights.

Drifter...you got a pm buddy.
Old 07-14-2005, 05:29 PM
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Default could be

they may be different, but they may be the same. heck they might even use the same exact part number for the module. i'd have to check the wiring diagram to see how much different they are. i was just trying to add some real life experience, and also wondering if this other situation worked out.
Old 07-19-2005, 12:24 AM
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you mean to tell me you hooked direct power to your ballast and didn't melt or burn your wires ??
Old 07-19-2005, 07:21 AM
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Default what'* the problem

yes that'* correct. that'* exactly what i mean to tell you. those things draw a little less than HALF the current of a normal halogen bulb... what'* the problem? they draw a lot of current to start up, but it'* only for like a millisecond. it'* never been a problem... and continues to not be a problem... did someone tell you to put a second battery in to run your HIDs?? lol


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