'96 850 wagon... multiple issues

[Ozark Lee]

First of all, whenever I go over an especially horrid pothole or bump, the check engine light turns on. Usually, it will turn off after going over another bump or when the car is off for long enough.

Changes are it is a bad connection on a sensor. Most of the chain auto parts stores will either read the codes for you for free or "rent" you a scanner so that you can check the codes. When I say rent, they charge a credit card for it but they fully credit the card when it is returned so it is free. If you can read the code when the light is on then you can figure out what sensor to check out.

The reverse lights are usually a sign that the PNP switch on the transmission is beginning to go bad. Here is how to replace it:

http://volvospeed.com/Repair/pnpswitch.php

The other lights only come on when I bring the key back a bit after starting the car.

Classic symptoms of a bad electrical portion of the ignition switch. A very easy fix:

http://volvospeed.com/Repair/ignit_switch.php

Recently, the car fails to stay on. The car starts, revs, shudders, and turns off.

Reading the codes might help with this one. As weird as the problems are when the ignition switch goes out the car will usually run fine. Idle problems often trace back to the MAF sensor. You can test the theory by simply unplugging the MAF sensor and see if it idles smooth again. That test will trip the Check Engine Light.

...Lee

[Ozark Lee]

The MAF sensor (Volvo also calls it the AMM or Air Mass Meter) is the tube next to the air filter box that has an electrical plug. On the Turbo models it is on the back side of the filter box and on a N/A model it is to the left of the filter box as you look at it from under the hood. Here is a picture of what you are looking for:

http://www.fcpgroton.com/product-exec/p ... gory_id/10

It is easy to disconnect, there is a metal wire spring on the plug - just squeeze the wire spring in and lift the connector off. Sometimes all you need to do is clean the MAF. The auto parts store should have aerosol MAF cleaner that you just spray on the sensor element and then let it dry. Never scrub the element and don't even touch it.

...Lee