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1980 242 Motor won’t turn off with ignition switch.
The original problem was alternator not charging battery. I found a broken wire to alternator/regulator and repaired it. It was the single small red wire with spade lug attached to voltage regulator on alternator. I forgot to disconnect the battery and wire did arc during reattachment to spade lug. Now motor will not turn off when ignition key is turned off and removed. The motor WILL however turn off properly if I disconnect this red wire from alt/reg terminal. I would leave it disconnected but of course battery will not charge properly. With the red wire attached the alternator is properly charging the battery. I suspect I may have trashed the built-in volt reg when I arced the wire but can this cause the motor to not turn off with the ingition switch?
(it's not the ignition switch, I swaped it from my other Volvo and it works fine with red regulator wire disconected...
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With key off:
Zero volts at red wire and alt terminal (attached or unatached)
With key on:
6.2 volts at red wire/alt terminal (with red wire attached)
9.3 volt at red wire only (when disconected)
zero volts at alt terminal (with red wire disconected)
Side note: The voltage reading on my other 85 Volvo is 1.8 volts (with key on and red wire attached to alt terminal).
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key on, engine off, wire disconnected, the red wire should have the same as the battery-12.5 volts or so. there's a short in the harness some place. backtrack and check both sides of the firewall connector, the round plug on the cluster. when you test the connectors, test plugged in and unplugged.
if the car shuts off when the red wire is unplugged, where is the voltage, or why does it stop running? id've bet you had voltage with the key off. i'd sure like to get my hands on this thing, the light here sucks and i can't see under your hood. keep trying, chuck.
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This is another post I found regarding voltage backfeeding through the alternator. Could thsi have anything to do with my problem?
Your rectifier diodes in alternator are faulty.
Take an AC voltmeter with it running and check for AC voltage, anything over 25 millivolts AC indicates bad rectifier diodes.
One of them is shorted and when you switch off key it is backfeeding through regulator circuit to alt light wire terminal and then feeding into cluster, with key off the other bulbs all combined provode enough of a ground path to light bulb. The alternator will pass a simple voltage output test but would fail an amperage (load) test if the diode(s) is (are) faulty. The remaining 2/3 of alternator is working when one of the diodes fail. Battery will stay up unless you drive slowly and have a lot of things on like lights and fan at same time.
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this failure of the alternator i've only seen leave the light in the dash on after the car is off. you have a crossfeed from that circuit to the ignition circuit. now i'm thinking there are 2 problems. it never occured to me the alternator should not be feeding voltage to the red wire while the car is off.
with the key off and the red wire unplugged, is there voltage on the wire? is there voltage on the terminal on the alternator? man, this is good. lemme know, chuck.
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humm, now this is getting interesting.
With key off:
Zero volts at red wire and alt terminal (attached or unatached)
With key on:
6.2 volts at red wire/alt terminal (with red wire attached)
9.3 volt at red wire only (when disconected)
zero volts at alt terminal (with red wire disconected)
Side note: The voltage reading on my other 85 Volvo is 1.8 volts (with key on and red wire attached to alt terminal).
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Here are a couple of questions to think about.
When you turn off the key, does only the engine keep running, in other words does everything else, radio, fan, lights go off as normally they would?
Where do the wires which power the ignition and the wire which goes to the alternator get close to each other.
Do they share any connectors or components?
I think it is most likely, as Colin UK said, that at some point that wire to the alternator is coming into contact with the wire to the ignition. The wire runs under the front of the engine and then through the firewall to the dash light. The ignition wire runs from the fuse box (does NOT go through a fuse) through the firewall. Along the fire wall to the ballast resistor on the rt of the firewall then back across to the coil and also to the ignition box and to the the starter (terminal 16, and I can't figure what this is for?????)
If your wire harness is bad then anywhere along the firewall there is potential for shorts. Also down at the starter where this wire to terminal 16 could be touching the battery cable to thestarter, In 1983 this wire is brown.
Explore (and a wiring diagram would help)
--
744-16v-4+OD 185kmi., 745-16v-4+OD 359kmi., 242Turbo-4+OD 170kmi?, 245DLT automatic 287kmi.
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the brown wire on the starter is the resistor bypass for the ignition. while the car is cranking, this is the path used to power the coil. once started, the blue wire from the fuse box takes over and the resistor is in the path. bypassing the resistor while starting makes the coil hotter. fyi, chuck.
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When the key is turned off the motor stays running. The radio and heater fan shut down. Alternator light never comes on. Noww this is where it gets weird...
With the motor running and the key off I actuate the turn signals and it makes a noise on passenger side (like solenoid) but does not come on. However the alt light glows dimly. It's like the turn signal is trying to work but do not have enough voltage. With key in the "on" position turn signals work fine.
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the ignition sw is turning off the fuse box, therefore the blower and radio go off, too. but that's a different side of the ignition sw that goes to fuse 1, 2 and 3. fuses 11, 12 and 13 are in the same circuit as the ignition system. the blue wire leaves the ignition sw, powers the 3 fuses with the fuse box acting as a jumper to send power to the engine harness, again, a blue wire. the turn signals are in this part of the fuse box, fuse 13. something is keeping the power on the blue wire with the engine off, this is backfeeding into the fuse box through the jumper and this lets then turn signals try to work.
the fuse box has color codes for the wires attached to it. 11 is blue, 12 is blue/yellow and 13 is blue/red. unplug all that stuff and see if the problem clears up. the blue wires from the ignition sw and out to the coil will be in there, but they should be closet to the body of the car instead of the outer portion of the box. look at where the blue/yellow and the blue/red are plugged in at the box, you'll see how to avoid unplugging the blue power wire from the box. still trying, chuck.
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I forgot to mention that the problem is somewhat intermittent.
The problem has corrected it’s self two time so far in two days
and then gone back to not turning engine off.
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This problem is almost certainly a short cicuit in the wiring.
The warning light terminal of the alternator rises from ground to battery voltage when the alternator is charging (that`s what makes the charge warning light go off)
A short circuit between the warning light wire and another wire connected to an igniton circuit will cause the problem you describe.
(The alternator is back-feeding the ignition system.)
Colin.
1990 740SE B200E/M47, remote C/Locking.
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Colin,
Would I have caused this short circuit when the wire arced?
I forgot to mention that the problem is somewhat intermittent. The problem has corrected it’s self two time so far in two days.
I’ve tried wiggling wiring harness with engine running and key turned off with no luck.
Where bouts in wiring harness would I look and do I have to split harness open over the entire length?
Thanks,
Dale
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pull fuse 13 and try again. keep us posted, chuck.
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Porkface,
Nop, pulling fuse #13 didn’t do it but then again it can’t not turn off if it can’t start, can it… Can we get serious and give me some help on this one, pretty please?
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ok, if the alt wire is plugged and you unplug the ignition sw, what happens then? chuck.
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OK, I tried that and now the muffler bearing seized up.
Start'in to think I'll have to break down and buy one of those new S40 racers.
Thanks allot man...
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what are you talking about-muffler bearing? you pulling my leg? if this wasn't real, thanks for the waste of time, chuck.
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It's a real problem all right. Read my original post.
btw, what's an ignition sw..?
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ignition switch, unplug it while the car is running and disregard the muffler bearings. what happens? chuck.
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When I disconect or pull the ignition switch completely out the car stays running.
Please read my post near the top titled "Could this have something to do with my problem".
I have an good running 85' 240 setting next to it for any comparisons that may be needed?
Sorry for the goofing, I thought you were pulling my leg...
Thanks
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