It is a 1988 240 wagon automatic.

After changing the coolant (and spilling it all over the engine bay) the car will not start at all.
The solenoid doesn't even attempt to click.
The dashboard behaves funny. When the ignition switch is on and you step on the brake pedal the MPH gague goes up.
So I believe something got fried with all that water spilling all over everything.


What should I check?

 

Check all the ground wires and the battery connections.

 

Could anyone tell me where the ground locations are?

I've checked the posts of the starter solenoid and this is what I've come up with.
The two big posts (bolt on) have +12v at all times. The lower big post is connected to the starter motor housing via a wire.
The flat post (blue and yellow wire) has +12v when ignition switch is turned all the way to the right (as if to start the motor).

Are these readings correct?

And I would love some more specific suggestions because I am not very familiar with volvos.

Thank you for reading.

 

alright well the car is still the same.

I've checked all the ground points on the body and on the block (all the ones I could find). They all have continuity to the battery ground.
The two big posts on the starter assembly get +12v like they should, and the flat bayonette post gets 12v when the ignition switch is turned.

I know it's not the starter itself because multiple systems are affected. For example, the radio doesn't turn on, the headlights and the brake pedal make the MPH needle gauge move up, the "ding ding ding" sound does not appear anymore when the keys are in the ignition, and I never hear a fuel pump start pumping.

I have checked all the fuses and they are good. I checked the important wires on the ignition switch harness and they are good as well.

Where else should I check? Is there just a diagram that illustrates all the grounding points on the car, inside and out? I really don't want to have to take it to a shop because It's taking me too long to figure out where to look.

 

Check the engine harness at the Main plug.
The wires might be shorting out.

 

Where is the main plug and what does it look like? And what am I looking for?

 

Should be mounted to a clip that mounts to the firewall at the back of the head.

It is a grey plug that has 6 or 8 wires going to it.