LT1-LT4 Modifications 1993-97 Gen II Small Block V8

MALF 16: Lo-Res Fail

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Old 04-27-2008, 05:34 PM
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Default MALF 16: Lo-Res Fail

Cruising the other day, and my car just dies, all of a sudden... I pull over, check the obvious, and go home to get my computer.

Just ran a DTC Check, and came up with MALF 16, which translates to "system voltage too low"

I replaced the ignition coil, and still nothing... the motor turns over, no problem, but will not fire up.

What would be causing this low voltage situation??? And cause it so suddenly? My battery is less than a year old, ignition coil was less than a year old, and has been replaced just yesterday, Opti is an MSD unit, and less than a year old... Bad ground somewhere? if so, where?

I don't have any computer mods done to the motor, or anything that would mess with the computer.

Any help would be awesome!
Old 04-27-2008, 05:46 PM
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the problem is the opti, check the connectors/cables to it. If they are good, then you need a new opti.
Old 04-27-2008, 06:01 PM
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MAYBE the ICM but, not sure. Could be sending a low signal to the coil, and thus the coil isn't putting out what it should. This is all purely a guess though.
Old 04-27-2008, 06:17 PM
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I'm starting to think (unless a loose wire has gone unnoticed) that it's either the ICM, or possibly a camshaft position sensor. I'm trying to research the camshaft position sensor, but can't find any info. on it. U guys know where it is?
Old 04-27-2008, 06:25 PM
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Alright, found a proper definition of the MALF 16 code:

Code 16- Low resolution pulse (distributor). ECM is not detecting the 4X pulse from distributor. Check wiring connections, especially the pigtail connector from the optispark to main wiring harness. This is the black/red wire that goes to terminal "A" on the pigtail connector. On the 1992-93 ecm, this is wire C5 (green connector). 1994-95 ecm, this is wire B2 (black connector). If wiring checks out, you will have to replace the optical sensor module in the distributor.

Time to check the wires... Given that my MSD opti is less than a year old, with less than 5000 miles on it, I can't imagine it's K.O.'d already.
Old 04-27-2008, 06:57 PM
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You can't imagine, but it's a fact that Opti-Sparks can live as little as a few days (from pretty much any company) and also be DOA right out of the box.

Lets hope it's a bad connection or the ICM. Problem with the ICM is it sits right on the head, which gets pretty hot. PCB, capcitors and resistors aren't a fan to heat and that can cause them to go out. Which is partially why there is the ICM Spacer mod (washers behind the ICM to space it away from the head.)
Old 04-27-2008, 06:58 PM
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Originally Posted by Formula350
MAYBE the ICM but, not sure. Could be sending a low signal to the coil, and thus the coil isn't putting out what it should. This is all purely a guess though.
low res pulse (code 16) is the opti, nothing else. it has nothing to do with the icm or any other ignition stuff, this is the optical sensor (cam position sensor) component of the opti
Old 04-27-2008, 07:00 PM
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Originally Posted by Dadic 78
I'm starting to think (unless a loose wire has gone unnoticed) that it's either the ICM, or possibly a camshaft position sensor. I'm trying to research the camshaft position sensor, but can't find any info. on it. U guys know where it is?
the cam position sensor is the opti lol
Old 04-27-2008, 07:44 PM
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no wonder I couldn't find any articles on it... :p Hey, I'm learning as I go...

So, would you think the entire Opti needs replacement? or is there a replaceable Optical Sensor component to the opti?
Old 04-27-2008, 08:12 PM
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It'd be better to just do the whole thing really. And get a true GM part, not an eBay "GM" part. You might pay more, but it's a nice piece of mind to have.
Old 04-27-2008, 09:40 PM
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I'm running an MSD right now... Figured buying the best name in the biz would be a good idea. Turns out I was wrong.



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