i just picked my car up from the shop. i spent 300$ on a ingnition switch and a PNP switch to fix my intermiten starting problem. it started right up but wouldn't start after the five minute ride home going no faster then 50 MPH it wouldnt start. when it doesnt start it doesnt even turn over nothing happens. i have tried to wiggle the shiffter but that didnt help. i have also replaced the batterie. The car will start fine when its cold and once it is started it runs fine. If i use it for a short trip it will not start or when its really hot and sunny out. I have been told that i needed the new PNP switch by many people but that wasnt the problem. what is wrong with it.

Are you saying that the problem is heat-related - that is, does it occur only or almost only when the weather is warm or the engine is warm? And is it the case that once started the engine doesn't stall? When the engine is running do the various electrical devices in the car work properly (lights, radio, defog, etc)? If these are true it makes the starting circuit a near-certainty.

If so - tracing the connections with a multimeter is really the way to solve it, but many questionable electrical connections act up when warm because the resistance of common materials increases with heating. Sometimes the surface of the connections looks ok but there is corrosion just beneath - especially battery, primary alternator, starter terminals (those that carry lots of current). Those could all go bad only when hot.

You need to get it to duplicate and have it diagnosed properly instead of throwing parts at it. The ignition contact plate and the gear position sensor were all solid guesses and probably would've worked on 90% of the 850 out there with those symptoms but unfortunately it did not work for you. It could be something as simple as a starter but without diagnosing it this is just a guess. Do you have access to a multi meter and know how to use it and read a wiring schematic because that is what you need to do. You need to get it to duplicate and go out under the hood and see if you are getting 12v to the little wire that goes to the solenoid on the top of the starter under the intake manifold. If you are then you more than likely need a starter if not then you need to see where that wire gets it's feed and trace it back up the line. I know this is probably not what you want to hear but it is pretty much the reality of the situation. You need to get this problem properly diagnosed and then get it fixed right.

Mark

If you are on flat pavement, turn key to off, put the tranny in gear, release the parking brake and move the car slightly back or forth. Then return the tranny to P or N and try starting the car. Has worked for me when my 855 had those symptoms.