Mechanics

CHECK ENGINE LIGHT

1999 Plymouth Neon

Computer problem
1999 Plymouth Neon 4 cyl Front Wheel Drive Automatic 136000 miles

The check engine light has been on and off for a couple months now. I have taken it to two mechanics now. Both of them found a code 340, checked the cam and all was good there. The second mechanic found two more codes--123 and 320. He checked what he could and said, again, that the mechanical parts were working.
Is this a computer problem or electrical. Or worse yet, both? I appreciate your help.
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Jennannetedder
March 26, 2009.



NOTE: Cam signal is monitored during engine cranking after a specified number of crankshaft position sensor signals have been detected. DTC may be stored in Powertrain Control Module (PCM) when no signal is received from Camshaft Position (CMP) sensor when crankshaft position sensor signal exists. Possible causes are: engine does not start, defective camshaft position sensor or target magnet, defective PCM, or defective connectors or wiring.
DTC P0340: NO CAM SIGNAL AT PCM
1.Turn ignition on with engine off. Using scan tool, check for DTCs. If global good trip counter is displayed and equal to zero, go to next step. If global good trip counter is not displayed and equal to zero, go to step 12 .
2.Turn ignition off. Disconnect connector at camshaft position sensor. Camshaft position sensor is located on rear of cylinder head, just below valve cover. See Fig. 39 and Fig. 40 . Inspect connector for corroded, pushed out, miswired or damaged terminals. If terminals are not corroded, pushed out, miswired or damaged, go to next step. If terminals are corroded, pushed out, miswired or damaged, repair as necessary. Perform TEST VER-5A .
3.Turn ignition on with engine off. Using voltmeter, check voltage at terminal No. 1 (Orange wire) on connector for camshaft position sensor. If voltage is more than 7 volts, go to next step. If voltage is 7 volts or less, repair open circuit on Orange wire between camshaft position sensor and PCM. PCM is located at driver's side front corner of engine compartment, between battery and fender. Perform TEST VER-5A . 4.Using ohmmeter, check resistance between ground and terminal No. 2 (Black/Light Blue wire) on connector for camshaft position sensor. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit on Black/Light Blue wire between PCM and camshaft position sensor. PCM is located at driver's side front corner of engine compartment, between battery and fender. Perform TEST VER-5A .
5.Turn ignition on with engine off. Using scan tool, monitor Camshaft Position (CMP) sensor state while momentarily connecting jumper wire between terminals No. 2 (Black/Light Blue wire) and No. 3 (Tan/Yellow wire) on connector for camshaft position sensor. If CMP sensor state changes, go to next step. If CMP sensor state does not change, go to step 7 .
6.Turn ignition off. Remove camshaft position sensor from cylinder head. Inspect target magnet and locating dowels for damage or misalignment. Replace target magnet and locating dowels if damaged or misaligned. Perform TEST VER-5A . If target magnet and locating dowels are okay, replace camshaft position sensor. Perform TEST VER-5A .

7.Turn ignition off. Disconnect connectors at PCM. PCM is located at driver's side front corner of engine compartment, between battery and fender.
8.Using ohmmeter, check resistance between terminals No. 1 (Orange wire) and No. 3 (Tan/Yellow wire) on connector for camshaft position sensor. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short circuit between Orange wire and Tan/Yellow wire
between camshaft position sensor and PCM. Perform TEST VER-5A .
9.Using ohmmeter, check resistance between terminal No. 3 (Tan/Yellow wire) on connector for camshaft position sensor and PCM connector terminal No. 33 (Tan/Yellow wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit on Tan/Yellow wire between PCM and camshaft position sensor. Perform TEST VER-5A .
10.With connectors at PCM disconnected, use ohmmeter to check resistance between ground and terminal No. 3 (Tan/Yellow wire) on connector for camshaft position sensor. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on Tan/Yellow wire between PCM and camshaft position sensor. Perform TEST VER-5A .
11.With connectors at PCM disconnected, use ohmmeter to check resistance between terminals No. 2 (Black/Light Blue wire) and No. 3 (Tan/Yellow wire) on connector for camshaft position sensor. If resistance is 5 ohms or more, replace PCM. Perform TEST VER-5A . If resistance is less than 5 ohms, repair short circuit between Black/Light Blue and Tan/Yellow wire between PCM and camshaft position sensor. Perform TEST VER-5A .
12.Attempt to start engine. If engine starts, go to next step. If engine does not start, perform TEST NS-SEL: NO START TEST SELECTION .
13.Turn engine off. Inspect wiring and connectors between camshaft position sensor and PCM. Camshaft position sensor is located on rear of cylinder head, just below valve cover. PCM is located at driver's side front corner of engine compartment, between battery and fender. If no problems exist, test is complete. If any problems exist, repair wiring or connectors as necessary.


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BMRFIXIT
Mar 26, 2009.