Chrysler Repair: 99 Concorde 2.7L stalls, camshaft position sensor, using a digital multimeter

Question
Hi Ronald,

I have a 99 2.7L Concorde with 94k miles.

Every time I start the car it runs fine on idle for between 30 seconds to 1 minute then it starts to splutter and eventually stalls. Also the engine management light is on.

I have changed the PCV valve, spark plugs, ran and engine flush and changed the oil.
I also ran a compression test on the cylinders, each one tested at around 180psi.

I then checked the trouble code, which were: -
P1684 - Battery has been disconnected in the last 50 starts (That was me)
P1391 - intermittent loss of CMP or CKP
P0356 - ignition coil #6 Primary Circuit

From the codes I tested the Crankshaft position sensor, the Camshaft position sensor and the connectors to each using a digital multimeter.

The Camshaft position sensor operation voltage went between 0.0 & 0.5 when turning the engine.

When testing the Crankshaft position sensor operation the voltage went from 0.0 to 0.42 (not 0.5) is this considered a faulty sensor and could it cause the P1391 error?

Is there anyway to clear the engine error codes without a scan tool?

The next thing I'm going to check is the ignition coil on cyilnder 6. Can you tell me if there is something else I should be looking at?


Thanks & Regards,

Eddie  

Answer
Hi Eddie,
On other things to check, I would suggest that you take a look at the egr valve to see if the valve stem might be stuck ajar which will cause stalling out at idle. See if you can move it freely via a flat blade screwdriver in the slot of the stem, and lubricate the stem with some penetrating oil.
Roland



Hi Eddie,
I don't have personal experience with the measurements that you have done on the sensors. But I do have the powertrain troubleshooting manual for the 2.7 and 3.2L engines. One discrepency is that you report the voltages as varying from 0 to about 0.4 or 0.5, but the manual speaks of it as a 5V signal, as does the Haynes manual for the 3.3 and 3.5L engines when cranked by hand. Were you measuring between the sensors and the sensor ground wire (black/light blue)on pin 43? Your lower values could just be an error in the dynamic response of your voltmeter. The manual uses a DRB III and a scope to look at the two signals with the engine running and suggests that if one or the other is below the expected value (has an irregular scope pattern) then that sensor should be replaced unless you can find a wiring problem as the explanation. The basis for the code is an intercomparison of the expected value of the cam sensor (based on the crank sensor leading and falling edge values observed at every 69 degrees) and its observed value. So I really can't relate exactly what you have observed to the powertrain in motion measurements observed with a scope. The possible causes for the discrepency are listed as:
open or shorted 8v supply circuit, open sensor ground, open or shorted signal circuit, excessive separation between the crank sensor and the crank pulse ring, excessive separation bwteeen the cam sensor and the target magnet, damaged target magnet, damaged pulse ring, failed sensor, failed PCM, loose or unlocked sensor connectors. So while the possibilities are virtually unlimited if one could view the scope patterns of the two sensors it might lead to the proper conclusion as to the cause. I will have to leave it to you as to what might be the best explanation.
On the #6 coil code, the test procedure is to probe the tan/light blue coil #6 driver wire with the engine running to see whether it does or doesn't show a steady 12V. If it doesn't, and instead goes on and off (blinks if you are testing with a light) then replace the #6 coil. But then it says if it isn't steady and bright you should check the resistance of the primary coil of that #6 and see whether it is 0.3 to 0.7 ohms. And then it says if it isn't steady and bright (but not blinking, though I don't quite understand the difference) then check the connector and tan/light blue wire for the driver wire from PCM pin 4 to the #6 coil for continuity. So again I am not clear what to make of this troubleshooting "tree". Perhaps you can make something of this.
As for erasing codes, the OBD-I system would do that if you disconnected the battery for a few seconds. But I haven't seen anything similar for the OBD-II system which is what you have there. You could try it and see what happens when you disconnect the battery.
I would be interested in what you learn further about this situation.
Roland