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2nd Gen Dakota 1997 - 2004 Dakota's

4.7L cranks, won't start

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  #1  
Old 08-30-2010, 11:15 AM
dyeager535 dyeager535 is offline
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Default 4.7L cranks, won't start

Hi! Hope the forum can help out here.

First things first, forum etiquette being what it is, I did do a search in this forum for this specific problem, and didn't have any luck.

My friend has a 2001 Dodge Dakota with the 4.7L engine.
The truck ran absolutely fine up until one day. Vehicle driven, parked, then wouldn't start.

The "problem" indications are that none of the gauges work (fuel, temp, etc.), the overhead console display comes on, but everything is zeroed out (battery has been disconnected...reason for this?). The compass MIGHT work. The gauge display says "no bus". The fuel pump does not prime when key turned to run. The engine turns over, but obviously doesn't start. Fuel pump does not run as the engine cranks. I checked the fuel rail pressure test port, and after a week or more of sitting, and intermittent attempts to start it, the fuel rail STILL had pressure (no pressure tester, just pushed in the valve and fuel came out under pressure), leading me to believe that the injectors are not being commanded to fire when the engine is turning over (probably same issue not causing fuel pump to run?). The PCM connectors have not been removed/cleaned/inspected yet.

The fuel pump relay has been swapped with the AC one (which works) and that didn't fix it. Key on/off/on/off/on threw codes "999", "920" and "921" if I remember correctly.

The owner had already pulled the bed off and purchased a fuel pump, so we swapped that, of course it wasn't the problem. But it gave me a good chance to do a rudimentary check of the wiring harness, and what I could see looked good. All the loom is intact, all the loom is still attached well to the body, all grounds I could see are tight and clean (to include up at the PCM). The truck has never exhibited any "random" problems before that lead me to believe it might be wiring or something else that wore through, or a ground that failed for whatever reason, etc. No recent work done on it.

The truck has lived in the NW for most of it's life, so there is no rust/corrosion to speak of, and based on the undercarriage and owners testimony, the truck has not been abused.

The owner has a copy of the service manual, but it's in PDF and a bit difficult to reference, not being hard copy. I don't know how to check for spark with this setup since it doesn't have plug wires. I expect no spark if the pump isn't being commanded to run...?

Appreciate any advice you might be able to give!
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  #2  
Old 08-30-2010, 09:27 PM
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cowboy63645 cowboy63645 is offline
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I dont know how much this is going to help you, but from what I have read any of the followig could cause the truck not to start: camshaft position sensor, crankshaft position sensor, throttle position sensor, coolant temperature sensor, and the MAP sensor. To check for spark, disconnect the ignition coil wire from the center of the distributor cap, connect a calibrated ignition tester to the coil wire, and crank the engine to check for spark. If no spark occurs, use an ohmmeter and check for resistance. The primary resistance should be between 0.6 to 0.9 ohms for the ignition coil. The coil wire should be between a minimum of 3,000 ohms per foot and a maximum of 12,000 ohms per foot.
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Old 09-01-2010, 01:06 AM
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Derek2002 Derek2002 is offline
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You said that you think that the injectors are not being commanded to fire.Check your ASD(Auto Shut Down) relay.Its located in the fuse box in the engine compartment next to the radiator fan relay.It supplies voltage to the injectors and coils.You can test it by checking continuity between terminals 85 and 86.It should be around 75 ohms.there should be continuity between terminals 30 and 87a also.Now hook a 12 volt power source from terminals 85(ground)to terminal 86(Positive).There should be continuity between 87 and 30.If any of these tests fail the relay is bad.You may also be able be able to swap out your radiator fan relay depending on what type on relay the ASD is.

If your relay tests good then your PCM may have shut down the ASD due to a low Crankshaft Position Sensor signal.

Hope this help you any.If it doesn't, post up let me know.
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Old 09-08-2010, 11:34 AM
dyeager535 dyeager535 is offline
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I appreciate the posts and time you both took to help out.

Owner spent some time with the service manual, however couldn't figure out how to conduct the camshaft position sensor test. Of course, that turned out to be the problem. I assume had the test been conducted (a bit tricky as it's tested still hooked up to the motor and wiring harness) it would have been found.

The "no bus" error threw me. Even the manual wasn't very clear on this error message apparently, although I'm not sure the owner dug into the manual far enough to make sure it wasn't described in there.

All that said, it's up and running now, just in time to put the motorcycle away for the rainy season.
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Old 08-23-2011, 06:27 PM
RobPooleJR RobPooleJR is offline
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Can we continue the fun on this thread? I'm going through a similar start however after replacing the cam and crank position sensors I still have an engine that just turns over and fouls plugs with fuel.

The Computer is reading RPM through the OBD2 while cranking.

Any thoughts?
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Old 08-23-2011, 06:27 PM
 
 
 
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