Will crank but not start

Tiny
TONY STEWART SR.
  • MEMBER
  • 1999 CHRYSLER 300M
  • 3.5L
  • 6 CYL
  • AUTOMATIC
  • 186,000 MILES
Got in it the other day when to start it and all it would do was turn over so I checked fuses and relays, none were bad that I could tell.I even used some relays from my Durango to test. Turns over good so I did not think anything was wrong with starter or battery so I looked at the timing belt and noticed the left cam was a little off sitting on the left dot not in the middle of the two dots, so I replaced the belt I bought from Autozone(dayco) brand. Since replacing belt no start so I moved to checking plugs, gaps within specifications at fifty. Condition of plugs pretty good except one has a little oil on it. Wanted to check fuel pressure but the way the schrader valve is sitting cannot get my fuel pressure gauge on it so I do not know what the pressure is. However, when key is turned to run I do hear fuel pump, so at least I know fuel pump is working. Doing the key dance only code p1684 and tried to hook up elm27 to my phone but it cannot connect to car. Really could use some help to figure this out.
Sunday, August 20th, 2017 AT 12:12 PM

8 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
The first thing to do is see if the automatic shutdown, (ASD) relay is turning on. Use a test light to back-probe the dark green/orange wire at the ignition coil pack, any injector, or either smaller terminal on the back of the alternator. You will see the test light turn on for one second when you turn on the ignition switch. What is important is if it turns on again during cranking. If it does not, the two suspects are the crankshaft position sensor and the camshaft position sensor. Those often do not set diagnostic fault codes just from cranking the engine. When that happens, you need a scanner to view those sensor signals. Both sensors will be listed as "no' or "present" during cranking.
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Sunday, August 20th, 2017 AT 6:34 PM
Tiny
TONY STEWART SR.
  • MEMBER
  • 5 POSTS
How critical is the timing? Does it have to be center between the dots? Because the left one is center but the right one is on the dot. Also, can I jumper the ADS relay just to see if it will crank? Thanks for all your help caradiodoc.
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Monday, August 21st, 2017 AT 7:05 AM
Tiny
TONY STEWART SR.
  • MEMBER
  • 5 POSTS
Okay I unplugged coil on number one cylinder took my test light hooked one end to negative battery post and stuck probe into the spade of the green wire turned key to on (test light lit up) slight pause tried to crank (test light did not light up) so I am guessing this means no spark, right? Also tried jumping 30 and 87 on ASD relay test light stayed lit through (oncrank) but nothing. No start. Could it be PCM or possibly anti theft kicking in? However, the security light on dash is not on or flashing. Just to add this the key can be pulled out in any position could that have anything to do with it?
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Monday, August 21st, 2017 AT 8:05 AM
Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Jumping the ASD relay isn't going to help. The Engine Computer turned it on for that one second when you turned on the ignition switch. That proves the relay and all it's wiring and circuitry are okay, and the computer has control of it. The fact the computer doesn't turn it back on during cranking is because it doesn't know the engine is rotating, and that is because the signal is missing from the crankshaft position sensor or the camshaft position sensor. When there is no fault code to say which signal is missing, you need a scanner to view those sensors. They will be listed with a "No" or "Present" during cranking.

Be aware too there should be a new fault code set related to the ignition coil you unplugged. That could confuse someone in the near future but it will self-erase after 50 engine starts. Normal procedure is to poke the probe of the test light into the connector, alongside the wire, through the rubber seal. Also, it makes me nervous when the terminal in the connector is probed. If you stick it in too far, it can spread the terminal. That is a common cause of intermittent connections days or months later.
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Tuesday, August 22nd, 2017 AT 6:59 PM
Tiny
TONY STEWART SR.
  • MEMBER
  • 5 POSTS
How can I test crank sensor and cam sensor and how critical is timing marks and thanks again for all your help
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Tuesday, August 22nd, 2017 AT 7:56 PM
Tiny
TONY STEWART SR.
  • MEMBER
  • 5 POSTS
Went to pick and pull today and picked up a crankshaft sensor came home and put it in and what you know it started so I just want to say thank you soo much for all your help Caradiodoc you made my wife's day. Thank you
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Wednesday, August 23rd, 2017 AT 6:00 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
Nice work, we are here to help, please use 2CarPros anytime.

Cheers, Ken
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Thursday, August 24th, 2017 AT 12:13 PM
Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
No, no, no. It has to be diagnosed first!

Actually, diagnostic fault codes don't always set for the cam and crank sensors right away or just during cranking. In that case you have to use a scanner to view them and see if they're listed with a "No" or "Present" to indicate whether their signals are showing up at the Engine Computer.

Regardless, very happy to hear you solved it.
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Thursday, August 24th, 2017 AT 8:46 PM

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