Code 16 but no symptoms??? not sure.

[Stonecold C-4]

I bought a 1993 LT-1 Base Coupe 6 months ago, and when purchased the owner told me it would need a battery soon. I checked the service date on the battery and it was over 4 years old on a 5 year battery, 3 weeks later the battery was dead so I bought a new one. Five weeks go by and the battery is dead again, I figured it was because I did't drive it much because I was out of town working 3 weeks out of the month. So as time passed it got down to where it was only good for a week at a time, now you jump it and drive and shut it off and it's dead. So the amp meter is just to the right of center making me think around 14 or 15 and when running with all the accessories on the headlights don't dim so I think the alternator is good. The "Passive Keyless Entry" light stays on all the time and it has since I bought it and when it's off the battery is dead, so I thought it was draining the battery down and researched and couldn't find anything. So I jumped the car today got it started watched the amp meter go from way right to where it should be and shut it off and pinned A & B and got a code #16 I have read a lot about Opti Spark and this Vette shows none of the symptoms I read about and by the way the Vette has 92346 miles. When you jump it it fires right up with a bump of the key and never spits sputter or dies instead runs like a champ when cruising or standing on it. Oh and by the time I the got the code to cycle to make sure I got all that was stored the battery was dying. Anyone have any ideas as what I should check or test and I don't have a FSM yet. Thanks :ugh

 

[Hib Halverson]

With respect to the DTC16: It's a fault with the low-res timing signal. While you could have a problem there, first thing I'd do is fix the battery drain.

You need a DMM which reads 0-10 amps. There are many places on the web, the CAC included, where you can find instructions on how to identify a draw. The Service Manual offers some instructions on troubleshooting that, too.

Fix that, then charge the battery and test it to verify the battery is still in good condition.

Next, either fix or disable PKE. You can disable it with instructions in the Owner's Manual.

Once you've got the car where the battery will hold a charge, clear codes, pull the coil wire and crank the engine for 15 seconds. If DTC 16 resets, the Factory Service Manual is your friend. The solutions are either, replace the ECM, fix wires and connections problem(s) or replace the distributor, however, I'd do none of that until you make sure the code 16 is not setting as collateral damage from the battery causing a low system voltage issue.

If you don't have the FSM, get one.

CAC sponsor, Zip Products has been my source for them. Zip keeps many in stock.

 

[Stonecold C-4]

Thanks very much Hib for your reply I'll get on this in the morning and start with the basics in the order you suggest and see where it leads and post my findings. Thanks again

 

[Stonecold C-4]

Update Code #16

So I took Hib's advice and started looking for a draw down and disarmed my Passive Key Entry by pulling the fuse so now that light is off for the 1st time in 6 months without the battery being dead. What I did find is that my vanity light was on, on the driver side visor it's hard for me to believe I never noticed it but if that where the draw down was coming from and I found no other then problem solved and yes I feel a little dumb but dumb is better than spending bucks. So I charged the battery and it's been 3 weeks and I wanted to wait and see with some time passing if the Vette would start or would the battery be dead. My indicator used to be I'd just look at the dash when walking by and if the PKE light was off the battery was dead, so when I opened the door and saw the inside lights on and bright as well I felt good. So I put the key in and she fired right up today with a bump of the key and drove great then I put the fuse back in and the PKE light came back on so I pulled the fuse out again, so now I'll tackle the PKE light issue next. I didn't get any remote key fobs when I purchased this car just 2 sets of keys and I did test the alarm and it works as it should, not sure if not having fobs would keep the PKE light on or not.

 

[96gs917]

Sometimes the door switch, especially the drivers side will not turn the lights out when you close the door. I have replaced that switch
twice on my green LT4. I always make sure the lights go off when I close the door, before I leave the car. If the light stays on, I usually
can jiggle the switch, or push the plunger in a few times to get the lights to go out. Those door switches are a known problem.