No start

Tiny
JEEP61
  • MEMBER
  • 1996 JEEP CHEROKEE
  • 110,000 MILES
Hi, I have a '96 Cherokee, 4.0, A/T. The Jeep cranks but doesn't start. At key on the fuel pump buzzes and the ASD relayy clicks for about 2 sec. When cranking I don't have any spark and the ASD relay doesn't seem to click.

The PCM has been checked and was OK, the crank and cam sensor have been replaced with new Mopar parts, the ASD swapped.

I bought it used in working condition and it started fine until it start showing this problem, I asked the dealer if there was an antitheft device but, according to the VIN there is none installed at least at the factory, however it does have powerlocks.

Any suggestion? Thanks,

Lou
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Wednesday, November 30th, 2011 AT 5:57 AM

4 Replies

Tiny
CARADIODOC
  • EXPERT
If it had anti-theft, it would run for a few seconds until the fuel pressure bled down. The place to start is by checking for stored diagnostic fault codes. You can do that by cycling the ignition switch three times from "off" to "run" within five seconds without cranking the engine, then the codes will be displayed on the odometer. If there are no codes, you'll need a scanner that can display live sensor data. Look at the cam and crank sensors to see if "present" or "no" is displayed. If both are displayed as "no", it's possible no code will be set in memory because the Engine Computer looks for a signal from one when it sees the signal from the other one. If both signals are missing, the computer doesn't perform those self-tests.

If both signals are missing, you'll have to check the common 5, 8, or 10 volt feed wire and the common ground wire.

You're a few steps ahead of most people with your dandy observations of the ASD relay.
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Wednesday, November 30th, 2011 AT 6:30 AM
Tiny
JEEP61
  • MEMBER
Hi, thanks for your prompt replay. I checked the codes and got 12 and 55, which doesn't say anything, I tried with a scanner (OTC Mindreader) but it could not comunicate with the vehicle. Another test I did was to disconnect the plug at the coil and hook up the DVOM to the + side, with key on I have 12V, for the usual 2 sec, before the ASD opens the circuit, which should show that, at least, the wiring in that circuit is OK. I will checked the wire as you mentioned, I was wondering if the ignition switch coul be responsible for that?

Lou
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Wednesday, November 30th, 2011 AT 2:13 PM
Tiny
CARADIODOC
  • EXPERT
Burned contacts in the ignition switch typically affect the circuit feeding the power windows, heater fan, and radio. The contacts for the engine circuit handle very little current. Passing the large current is the job of the ASD relay.

Code 12 means the battery was disconnected within the last 50 starts. If it was not, look for an intermittent electrical connection that would make the Engine Computer think it was. Code 55 just means "end of message". Any other codes that might have existed would have been erased if / when the battery was disconnected or run dead. If no other codes come back, you'll have to use a scanner to view live data to see what's going on. The Chrysler DRB3 scanner has a "no-start" menu that shows all of the pertinent information on one screen. Normally when the ASD relay doesn't turn back on during cranking, the problem is related to the cam or crank sensors, the common feed and ground wires, or a timing chain or belt problem.
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Wednesday, November 30th, 2011 AT 9:10 PM
Tiny
JEEP61
  • MEMBER
Hi, I will checked the wires related to the crank and cam sensors, and see if I there is any problem. If all checks out ok then I will have to get it to a shop or dealer and get it scanned. Thanks.

Lou
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Sunday, December 4th, 2011 AT 3:38 AM

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