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Discussion Starter #1
Hey everyone,
First off, the car is a 1988 turbo automatic. I'm having an issue where the super monitor and the radio continue to stay on after the switch is turned off. Had the car about a year and finally got it on the road after fixing the bhg from the po and the issue has always been there whilst in my possession. The first thing I checked was the radio wiring since it had an aftermarket head unit it in, but the wiring looked good and I pulled the radio harness as well to check, still stayed on. Next I checked the ignition switch per the TSRM since I noticed the key could come out(the key looks very worn and will only come out if you jiggle it). The switch tested good and showed no continuity anywhere in the lock position. I even kept the switch disconnected and they remained on. I'm getting about 174 ohms of resistance between the grey and blue w/yellow wire on the radio harness, making me believe that I have a short between IGN and B+. I've pulled the fuses for both the radio and cig and the problem remained. If I pull the dome fuse in the driver side kick panel the clock and radio shut off, but I'm assuming this is because that's the power feed. At this point, I looked at the TSRM and went to check the engine fuse box and noticed that the RADIO NO1 fuse was out. I have a hard copy of the manual for a 92 since it was $27 and not $85+ for an 88 and it lists that same fuse as a DOME fuse and not radio. When I put that fuse in, I can take out the dome fuse in the driver side kick panel and the problem persists, leading me to believe that the short is somewhere between the engine fuse block and the accessory wiring. To further back up my guess, the cigarette lighter has roughly 9.5v with the fuses in and full battery voltage when the key is switched on and the radio will shut off and flicker between power states when another electrical load is applied to the circuit, another hint at a short. I did a wiggle test of the main looms for the radio and cig harness and the continuity between the radio terminals never changed. I'm trying to see if anyone knows and particular areas where a short like this may occur and/or any other electrical components that may have shorted internally. I've searched on here and found some similar threads, but most pertain to either the switch being bad or a radio harness being improperly installed(I had wished this was the case, but unfortunately not). Sorry about the huge post, I just wanted to make sure I gave as much information as I could as to what the problem is and what I have done to determine it's cause. Thanks in advance for any help.
 

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Discussion Starter #2
Well figured out some more stuff today. The radio acc wire gets around 9 volts with switch off, but if I remove the cig fuse it is 0. Super monitor stays on though so I kept looking. With the dome fuse in, the power wire for the cigarette lighter gets 9 volts all the time, so I removed the cig fuse and had continuity between the power wire and both terminals on the fuse block for the cig fuse spot and only continuity on one terminal with the dome fuse removed. This has me to believe that something in the dome circuit is shorting power to the ignition. Trying to figure this out since I'm putting a raspberry pi in here for a project but need my ignition power to be reliable and not keep things on. Any ideas?
 

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Discussion Starter #3
Actually just noticed that the super monitor stays on with the dome, radio(inside), and cig fuse all removed. Only way to get the super monitor to cut off is to remove the radio no. 1 fuse from the engine compartment fuse block. Must be a battery constant wire touching ignition somewhere.
 

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Discussion Starter #5
Just wanted to post an update here in case anyone has this problem in the future. Did a lot of tracing and reading wiring diagrams and finally found my issue. The previous owner apparently rigged the power antenna to always come on since he put an aftermarket radio in and didn't wire it right or something. He crossed some wires to where power was feeding back into the circuit with the key off. Unplugged it and my clock cut off and stayed off and only cuts on with the switch.
 

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Yeah, the 9V was the clue. A shorted wire in the car is not going to create 9V. That is a only going to happen of the power is flowing through some electronics that have a few semiconductors in the path. Glad you sorted it out.
 

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Nice job sorting it out, aftermarket head unit and how someone wired it up can always cause headaches!
 
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