Contour Enthusiasts Group Archives Forums General Troubleshooting "Crank No Start" problem solved !

I have a 95 Mistique 2.0.

It happened the first time in a very hot summer day after driving.

This week, it was cold. The car parkered overnight. Just cranked, cranked, and the engine could not catch up. It happened randomly and more frequently every since Monday.

Problem found finally! It is the connector on the Crankshaft Position Sensor! I beleive it was broken long time ago. Oil and dirt gradually eat up the contacts inside. Whenever I disconnect this connector, it will crank forever. If I connect it, it fired up immediately.

Hope it helps for you.+

Had one on my Saturn that was intermitent....Was harder than cane to find. Had to leave with dealer and they had to drive it every once in a while until it stalled on them and then they diagnosed it........sheesh you would think they would have better diagnostics......they had the car for a week.

You know, all the tests in the world will pass if the car is not acting up. Unlike most people think, the computer doesn't tell all. If it logs a code, then it only directs us to the system that is malfunctioning. Wiring, sensors, or a related system malfunction could all be the root cause of the problem. Crank, no start concerns are difficult to diagnose because the engine only logs codes when it is running. If a crank, no start is intermittant, then we have to have testing equipment on the vehicle at the time of failure to determine what we're not gettting. Better diagnostics would be nice, but we can only work with what we have.

I posted here last week about the crank no start 95 mystique. it still turns over only on the 1st crank every 2.5 hours. i am not too sharp with cars, how can i check the connector on the Crankshaft Position Sensor?

Turn the key on - does the CEL come on? Then turn the key to start - does the CEL go off during cranking? If so, the pcm is recieving an rpm signal from the ckp.

1. Measure Voltage
1.1 Disconnect battery negative cable from its post
1.2 Measure the voltage between the negative cable and the negative on the battery
1.3 I found it was 12 VDC (It should be 0 VDC)
1.4 Discconect one fuse at one time, and find out when the voltage drops down to 0VDC
1.5 To my case, I disconnected the power cable between the alternator and the battery. The voltage droped to 0VDC. However, the alternator was OK and checked by a shop. I look the disgram, found out that the Crankshaft Position Sensor is also connected with the alternator. That was the reason I checked the condition of this sensor.

2. Test
2.1 Clean the connector
2.2 Disconnect the connector, it repeated the problem everytime, just cranked forever
2.3 Connect the connector to the sensor, it fired up everytime.

Hope it helps.

Please take these comments from a 30 year veteran of electronics testing as constructive comments:

Your assumption in step 1.3 is incorrect.

You SHOULD read battery voltage during this test because there are circuits that are supposed to be hot all the time, for example, the clock and the computer memory. You SHOULD read supply when the "ground/return" is open. When you measure across an open, you should read the full supply voltage.

The reason the voltage dropped in step 1.5 is that you finally removed power from the circuit.

Sorry, but your diagnostic method doesn't do anything to lead to the diagnosis of a faulty crank sensor or connection.

Glad it's working anyway.

Steve

Just a note to say my crankshaft position sensor was acting up when the car got hot. In the end, unplugging and replugging it got rid of the problem for me. I still have the new one, and I will get it replaced (100k miles, might be a good idea.) But if you're stuck might help you out in a pinch.