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I first posted this in the general area and then saw this specific Datona forum. Hope posting it here also isn't a problem. I'm new to allpar today.

I have an '84 Daytona with turbo that has been garaged and not started in over 6 years. Ran fine before that. I have the Chrysler service manual for the car purchased when I bought the car new. I'm the original owner.

I get two fault codes: 12 and 42. I understand 42 but not 12. The shop manual states the following: "CODE 12 indicates a problem in the stand-by memory circuit. This code appears if direct memory feed to the Logic Module is interupted." I would have thought the "stand-by memory circuit" was in the Logic Module, but I do not get Code 44 which indicates a problem in the Logic Module.

I've made quite a few tests. The ASD relay (or fuel pump relay) is shutting down in about a second. However, I get a spark before shut down. Pulled all 4 plugs and tried starting numerous times to see that a plug fires once each attempted start. All 4 have fired at different times. I have pressure on the rail and appears the injectors are not plugged as I get a mist in the cylinders when I apply current to the injectors. I did a successful continuity test on all the lines from Power Module and Logic Module connectors (disconnected from the modules) to the source input/interface connector (also disconnectred). The Power Module puts out 12v, 7.5v and 5v to the proper circuits. The grounds are all OK.

I presume that Code 42 is triggered because of the Code 12 problem is causing the Logic Module to interupt the starting sequence. What is the "stand-by memory circuit", and what "direct memory feed to the Logic Module" could cause the problem in the "stand-by circuit"?

Thanks to anyone who can give me a lead on this.

Perry
 

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Code 42 1984 model injector circuit 1 open or shorted
1986+ models: ASD relay open or shorted

Your injectors may not be firing. Check the braided ground strap from firewall to intake manifold to be sure it's intact. And measure the resistance across each of the injectors.
 

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Code 12 can be set any time there is a battery disconnect. it also seems to show up any time any other code is set. In most cases, simply ignore the 12.
 

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I just double checked my 84 FSM and it shows 42 as the ASD problem. How is the battery in the car? I have a 89 Lebaron and the battery was over 5 years old, and it was good enough to start the car, but wouldn't hold a charge, so after a while the car would die, and I would have a hard time starting the car. It would start, sputter and die. It gave the ASD code. I put a new battery in the car and it hasn't happend again.
 

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Discussion Starter #5
Thanks for the comments.

1) Braided ground strap from firewall to intake manifold is good, and to confirm, I got 0 ohms from firewall heat shield to intake manifold. I get 0 ohms across each of the four injectors. Also get 0 ohms from Power Module connector pins (on the disconnected connector, not on the Power Module pins themselves) 4 to 8, and 5 to 8 (circuits Y12 - Z1 and Y11 - Z1; FSM CV24 7 & 8 wiring diagram page 8-876 & 8-877)). I agree the injectors are not firing long enough. I think this is because the ASD is shutting the power off to them in under a second. The mystery is why the Logic Module (LM) is grounding the ASD and interupting the sequence.

2) I don't think Code 12 is battery disconnect on the 84 Daytona. I think Code 11 is set on battery disconnect if you check codes before trying to start the car. I toggled the ignition more than 50 times after disconnecting and reconnecting battery which should clear codes for problems repaired or that cease to exist. Per FSM page 14-98, ON BOARD DIAGNOSTICS, 30 ignition toggles should clear all repaired/fixed codes. Note, both codes 12 and 42 remain after the ignition switch cycled over 50 times.

3) I think the battery is OK. To check, I swapped the battery from my Jeep which starts first time every time (including after swapping them back), and no success on the Daytona.

Any other tests/checks anyone can suggest?
 

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A no start problem is easiest to find. Since the ASD relay stops both power to the ignition and fuel and turns on when rotation is detected the problem is what is turning off the ASD relay. How long does it crank before spark occurs? Should be a couple of strokes. Key on should give two seconds or so of fuel pump operation so you have fuel pressure. Crank, fuel and spark = run. My book does not have 12 or 42 codes. A factory service manual is a great investment as it costs less than nearly anything diagnosed at a shop.
 

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The original post was nearly 2 years ago. I would hope he has gotten it started by now.
 
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