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Discussion Starter · #1 ·
I am building a trike with a 2002 dodge grand caravan as the drive train. This was my daily driver for over 10 years. I cut away the body leaving the entire front intact. Removed dash leaving wiring intact. Motor ran fine until I started cutting out unwanted circuits. airbag squib lines replaced with 3.3-ohm resistors. Dash controls removed, overhead controls removed. Headlights work, motor cranks no start. I have an injector pulse but no ignition pulse. I do have voltage at the coil and injectors. No ignition pulse at any coil input equals no spark. I am fairly sure I remove some wires that need to be connected just not sure which. Any guidance or guess? Willing to try anything.
 

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2013 Dodge Grand Caravan
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What engine? Diagrams are slightly different for each.
 

· 3rd Gen Plebeian
1997 Plymouth Grand Voyager Rallye
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Can you pull diagnostic codes out of the OBDII port?




ENGINE START-UP MODE

This is an OPEN LOOP mode. The following
actions occur when the starter motor is engaged.
If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the ASD relay and fuel pump relay. These relays supply battery voltage to the fuel pump, fuel injectors,
ignition coil, and oxygen sensor heating element. If
the PCM does not receive the camshaft position sensor and crankshaft position sensor signals within
approximately one second, it de-energizes the ASD
relay and fuel pump relay.
The PCM energizes all injectors until it determines
crankshaft position from the camshaft position sensor and crankshaft position sensor signals. The PCM
determines crankshaft position within 1 engine revolution.
After determining crankshaft position, the PCM
begins energizing the injectors in sequence. The PCM
adjusts injector pulse width and controls injector synchronization by turning the individual ground paths
to the injectors On and Off.
 

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Discussion Starter · #5 ·
Can you pull diagnostic codes out of the OBDII port?




ENGINE START-UP MODE

This is an OPEN LOOP mode. The following
actions occur when the starter motor is engaged.
If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the ASD relay and fuel pump relay. These relays supply battery voltage to the fuel pump, fuel injectors,
ignition coil, and oxygen sensor heating element. If
the PCM does not receive the camshaft position sensor and crankshaft position sensor signals within
approximately one second, it de-energizes the ASD
relay and fuel pump relay.
The PCM energizes all injectors until it determines
crankshaft position from the camshaft position sensor and crankshaft position sensor signals. The PCM
determines crankshaft position within 1 engine revolution.
After determining crankshaft position, the PCM
begins energizing the injectors in sequence. The PCM
adjusts injector pulse width and controls injector synchronization by turning the individual ground paths
to the injectors On and Off.
Yes I can pull codes from the obd. Scan shows p1495 (normal with several vacuum lines open) p0352,p0353 (yep no spark signal) maybe should put a test lamp on the ASD output make sure it is staying active.
 

· 3rd Gen Plebeian
1997 Plymouth Grand Voyager Rallye
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1,434 Posts
Yes I can pull codes from the obd. Scan shows p1495 (normal with several vacuum lines open) p0352,p0353 (yep no spark signal) maybe should put a test lamp on the ASD output make sure it is staying active.
I'd check the coils first with those codes. Do you know how to measure primary and secondary resistance on a coil?

Check the signal wire between the PCM and coils.

Check voltage drops- battery to coil, coil positive to negative, coil negative to chassis ground. Battery to PCM B positive, PCM B+ to negative, PCM Negative to ground.
Finally, voltage drop from coil negative to PCM Negative.


Fuel injected vehicles are extremely sensitive to ground path issues. You probably cut or removed a ground path. As good as you think everything on your project is grounded, I can guarantee that it is subpar compared to what an EFI computer actually wants, that's often the case.
 

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Discussion Starter · #7 ·
I'd check the coils first with those codes. Do you know how to measure primary and secondary resistance on a coil?

Check the signal wire between the PCM and coils.

Check voltage drops- battery to coil, coil positive to negative, coil negative to chassis ground. Battery to PCM B positive, PCM B+ to negative, PCM Negative to ground.
Finally, voltage drop from coil negative to PCM Negative.


Fuel injected vehicles are extremely sensitive to ground path issues. You probably cut or removed a ground path. As good as you think everything on your project is grounded, I can guarantee that it is subpar compared to what an EFI computer actually wants, that's often the case.
I haven't checked for voltage drops yet. My first issues when cutting out the rear wiring was with grounds going to the seatbelts. Multiple grounds tied to body bolts were required to start. I did measure resistance between grounds today. The battery to the body is zero ohms. Various engine metal parts were from zero to 10 ohms. Planning on making some new grounding straps.
 

· 3rd Gen Plebeian
1997 Plymouth Grand Voyager Rallye
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Grounds are complicated, not simple like older cars. The ground distribution section of the service manual is like 30 schematics long.

There should be practically 0 ohms on any of them.

61069





There are 11 major ground points-
61070
 

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Discussion Starter · #9 ·
Grounds are complicated, not simple like older cars. The ground distribution section of the service manual is like 30 schematics long.

There should be practically 0 ohms on any of them.

View attachment 61069




There are 11 major ground points-
View attachment 61070
I am interested in what PDF this is from. The page number and diagrams do not match the one I have. I believe mine is for 2004, not 100% sure. I have found several places where wire colors do not match.
 

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Discussion Starter · #10 ·
I am interested in what PDF this is from. The page number and diagrams do not match the one I have. I believe mine is for 2004, not 100% sure. I have found several places where wire colors do not match.
Doing a quick search I was able to match your pages to another manual. I was able to download a copy. May or may not make a difference but darn glad you posted this diagram.
 

· 3rd Gen Plebeian
1997 Plymouth Grand Voyager Rallye
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1,434 Posts
2004 is significantly different from the 2001-2003. They completely altered the engine electronics in 2004
 

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Discussion Starter · #12 ·
How well I know about the engine electronics changes. This motor is actually an 2006. Had to do major sensor swapping and timing hardware changes. After over 10 years and being the second owner I trust this drivetrain. I got the van from a close friend who bought it new.
 

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Yup, 2004 diagram will not work. 2001-2003 were the same, and very similar to 1998-2000 3rd gen wiring.

To get a newer engine like the 2006 to work in the 2002, you would have needed to swap the timing gears/chain/cover and sensor, and the flex plate. Then swap the 2002 engine wiring harness to the 2006 engine.

Possibly a problem with the body wiring/bus? I've read of these vans not starting because of a broken power sliding door wire harness before. Now that you have the proper year wiring diagrams, you'll have much better chances at finding the problem.
 

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Discussion Starter · #15 ·
You are correct on the parts swapping for the 2006 motor to the 2002 van. Also had to swap the intake and fuel system. I do have some pics and videos of the project. Covid and having to try keeping a restaurant running ate all my time in 2020. I will have to figure how to post the pics here.
 

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2013 Dodge Grand Caravan
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Fuse 16 (25A) and the ASD relay control the power to the coils. If not that then it's wire tracing time.
 

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Discussion Starter · #18 ·
Yup, 2004 diagram will not work. 2001-2003 were the same, and very similar to 1998-2000 3rd gen wiring.

To get a newer engine like the 2006 to work in the 2002, you would have needed to swap the timing gears/chain/cover and sensor, and the flex plate. Then swap the 2002 engine wiring harness to the 2006 engine.

Possibly a problem with the body wiring/bus? I've read of these vans not starting because of a broken power sliding door wire harness before. Now that you have the proper year wiring diagrams, you'll have much better chances at finding the problem.
Funny you mention the sliding door harness. The ground wiring for the sliding doors is exactly the straps that are behind the seats. No ground here equals no start. I believe I am hunting an ASD issue. I know the fuse and the relays are good and in the run position, I have power to the coil pack and to the injectors. In the start position, this power is off. I plan on checking the start/run outputs on the relay and the airbag module today.
 

· 3rd Gen Plebeian
1997 Plymouth Grand Voyager Rallye
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I believe that the ASD relay powers the fuel pump relay.
 

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Discussion Starter · #20 ·
I believe that the ASD relay powers the fuel pump relay.
Did a fair bit of testing this evening. ASD relay work ok, swapped in another just to test. When turning the key on the ASD relay engages sending power to pin 30. This powers the fuel pump injectors and coil. The problem, it disengages pin 30 within 1 second. The fuel pump follows the same procedure. The signal to engage and disengage the ASD relay comes from the PCM. What issues prompt the ASD relay to shut down the engine?
 
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