I drove my 850 to a job site yesterday, after I was done I drove down the hill for a burrito. When I got into my car and turned the key, nothing!

Horn is strong, battery = 12.7 VDC, idiot lights all light, but when I turn the key nothing happens. Fuses all good. Tried in Park and Neutral, bumped shifter in case neutral safety switch was stuck, nothing. Automatic transmission.

I thought maybe the security system disabled the ignition. I deliberately tripped it, put the key in the lock to turn it off, that didn't do it either. Security system LED is blinking normally.

Disconnected the battery and let set for several minutes, reconnected, in case it might reset something. Nada.

Had the car towed home. Frankly, I'm out of ideas.

Although:

The car was a gift December before last. There has always been a problem with starting the car and any combination of headlights not turning on/shifter won't unlock was solved by my #2 son who discovered smacking the steering wheel in the center (centre) made it work. Oh, the horn button also shorted a couple of weeks after I got the car and is disconnected and bypassed. Been running great until yesterday when the above happened.

I'm thinking ignition switch or ignition module (does it have one?)

I'm open to ideas, and I can't afford a mechanic as I just lost my job a week ago today.

Any help would be extremely helpful!

Thanks,
Chris
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EDIT: I'm now convinced that the ignition switch is okay. I tested for voltage at the spark coil and it's working. The relays all click when the key is turned and I can hear what sounds like a motor trying to run (or is running) under the black plastic cover over it and the pulley for the accelerator cable.

Can/Will a bad starter prevent the engine from even trying to turn over?

 

I would start with the ignition switch and the starter.

 

The starter is simply an electric motor. It takes an enormous amount of electricity, so it must be turned on by a solenoid, which is mounted on it directly. The solenoid is turned on by a set of contacts in the ignition switch which aren't related at all to the contacts that do all the things that cause the car to actually run. You can see why that would be - the car has to run all day, but the starter motor is only one for 1 second, and that 1 second is controlled totally by you, personally, the driver. It's not controlled by the same contacts in the ignition switch as the ignition, or anything else. I mention that to say that power at the ignition coil doesn't tell you anything.

I am not sure how the safety interlock with the shifter is worked into that circuit, but the volvo repair manual would address that. You should expect that circuit can be interrupted when you're not in park or neutral, and that switch could be the issue.

Normally, to troubleshoot this problem, you determine whether or not you have power at the solenoid to turn it on when you command it with the key. If you do, then you don't have to worry about all that wiring. The problem is the stater itself. Common problem.

Alternatively, you can test the starter and its power supply and bypass the ignition switch. To do that, you power the solenoid directly from the battery. Make sure it's not in gear when you do that.

 

Depending on your skills, you should go through it and test if the starter is getting a signal from the ignition.

If you don't know how or don't want to mess with it under the intake I think from the description of hitting the steering to fix electrical issues replacing the ignition switch would be the thing to do first and see if it fixes your problem(s).
The switch isn't that expensive and they are write-ups on how to and it's pretty easy, few tools needed.

 

I had that issue recently. The starter needs a certain amout of volts to crank. The problem I had was the pos battery cable. The connector was corroded between the wires. I had to take the connector apart and scrape the corrossion from between the several wires, since then I have been good to go.

I actually replaced my starter and still NO CRANK. Clean the connection real good and all is well. Put an ohm meter on the starter connection and see what the volts are. Just turn the key on to check it. Compare the reading to the battery.

 

Watch the last 3 minutes.

 

I came on this thread to find a solution to the same problem and discovered that sometimes the simplest explanation is the best. My 850 would not turn over all of a sudden because I left the transmission shift lever in "drive" when I parked last night. Once I moved the lever to "park" the car started up just fine.

 

Lawn mower syndrome. RobertDIY on youtube had a very good video explanation of why this plagues these 5cyl motors particularly. But it’s called “lawn mower syndrome” bc, say, you start the car just long enough to move it from in front of garage to get the lawnmower out. And essentially you get left with a motor that has one or two cylinders flooded or pressured up that you cannot overcome with the starter. Easiest solution is to avoid these quick stop/starts by leaving motor run a bit longer or ripping around the block once or twice, work on drifting the brick.

I had it happen when running a few blocks down to auto parts store, perhaps a 3 minute drive.