1996 850 Starter wire voltage when ignition switch in on position

[Kiprick]

I'm new to this, and, for that matter, any online forum. What can I say, I'm old! I've not been able to find what I need by searching so I'll ask. I have 1996 850 base with automatic. Recently replaced starter but new one failed after two weeks. In checking voltage on green starter wire I find that I have 12 volts when ignition switch is in start position. No surprise there. What did surprise me is that I have 11.3 volts when switch is in the on position. I would have thought there would be no voltage going to starter until switch is turned to start position. Any help appreciated!

[abscate]

I'm new to this, and, for that matter, any online forum. What can I say, I'm old! I've not been able to find what I need by searching so I'll ask. I have 1996 850 base with automatic. Recently replaced starter but new one failed after two weeks. In checking voltage on green starter wire I find that I have 12 volts when ignition switch is in start position. No surprise there. What did surprise me is that I have 11.3 volts when switch is in the on position. I would have thought there would be no voltage going to starter until switch is turned to start position. Any help appreciated!

Welcome Mountaineer! You’ve not only conquered a new mountain, you’ve found the friendliest auto forum in the world. We pride ourselves on being both new folks and female friendly, unlike many auto Fora.

Your car has a pretty classic failure of the electrical part of the ignition switch. I’ll link To the part number and a DIY thread ( topic covering you car repair ) shortly.

You diagnosed it perfectly by looking at the voltage on the green starter wire with ignition on, not cranking, that’s should be at 0 volts.

It’s about a $50part, 15 minute repair

There are a couple of versions of switch so use the part tool on one of our sponsoring vendors to nail that down, links to all are above.

Repair here.... your part number for your 1996 will be different
https://www.matthewsvolvosite.com/forum ... 88#p281688


Here I see a thread on root failure.

https://www.matthewsvolvosite.com/forum ... ot+failure

[Kiprick]

Thank you for the response! Bad ignition switch was my first thought after new starter failed, so I replaced it with new switch. No difference in voltage readings. When original starter failed I bought a new one and installed it. Reconnected neg battery terminal, turned the key and it started right up. But when I turned it off I heard a rather loud humming sound. Couldn't really tell where it was coming from but when I put my hand on the starter I could feel the vibration in it. Immediately disconnected battery and of course the humming stopped. That's when I replaced ignition switch. Still get same voltage when switch in on position. Now im getting a sore place on my head from all the scratching!

[abscate]

There is a starter relay in the circuit and it sounds like that is stuck closed, or else you have a wiring problem and the relay is getting a 12 volt trigger signal closing it uncommanded

The relay would be a better probability tha; a wiring fault unless there is clear evidence of wiring tampering.

Up link there is a topic on how to find wiring diagrams online to guide troubleshooting

[Kiprick]

From the posts I've read I gathered the 850 didn't have a starter relay. Where would i find it? Replacing it sounds much easier than trying to find a wiring fault.

[Kiprick]

Another thing that's got me puzzled...with 11.3 volts to green wire why doesn't starter engage when ignition switch is turned to on position? Also, I can hear starter disengage after engine starts and key is released and switch goes back to on position.

[abscate]

It might be getting enough voltage to spin but for some reason the solenoid isn’t engaging. Weird but not unheard of.

The wiring diagram will settle the start relay questions

[jimmy57]

There can be a resistor in some relays that shunts voltage spikes from relay coils, in this case the solenoid. Use a test light and go between ground and the green wore. I bet that voltage you see is not supported by any current flow and the light won't even light. The much more important test for a no start where you suspect bad starter is to check voltage on green wire with it plugged on solenoid to see what it is when key is in start position. Actually the most useful is to go between batt POS and the green wire and see what the circuit voltage drop is. I know there is either a jumper or an alrm relay in the circuit on 850s but to be honest I can't recall if there is another re;lay. If not then the neutral safety switch contacts in gear position sensor/neutral start switch assembly or wiring connections to that are on the list of suspects. IF the solenoid circuit voltage drop is low, < 0.5V during starter operation then you have a problem. NOTE: the initial instat of first solenoid engagement will be a higher voltage drop as you are powering two windings in the solenoid initially. Once the contacts close to send power to the starter motor brushes the pull in winding of solenoid goes off and the current draw drops. The hold-in winding then is the only current draw on green wire. The pull-in winding set grounds through positive brushes through armature out through ground brush. When the power is applied to the positive brushes the current flow stops in pull-in winding.

[Kiprick]

Thanks to both of you for the guidance! I'll pick up a test light tomorrow and let you know what i find.