No Engine Feed
Use this section if the engine cranks when the ignition key is turned to the "start" position, but there is no spark, fuel, etc. Also, the accessories and instrument panel work. This problem can have several causes and may take some time to track down.
Basically, most of the engine's components that require 12V get it through the J2 or Z1 feeds. The Z1 feed is basically the J2 feed switched on and off by the ASD Relay. On 1987 and earlier models, the ASD relay was located inside the power module. For later models, it was a black plastic relay located externally, near the other relays. The ASD Relay is controlled by the computer and is turned on when the computer detects a signal from the ignition reference sensor.
The J2 feed supplies power to all of the solenoids, some relays, the alternator field, oxygen sensor, diagnostic connector, etc. It almost always is a dark blue 14 gauge wire. If you do not see a dark blue wire, look for a common wire color on all of the solenoids. This should be your J2.
Turn the ignition key to the "on" position.
With the negative probe of your meter grounded to the chassis or negative battery terminal, use the positive probe to check for the J2 voltage at a solenoid. Look for the common wire color (usually dark blue). Now check for it at all solenoids, any relay that has that wire, the alternator field terminal (usually the top one, see the battery connections diagram in the No Power At All section), and at the power module, SMEC, or SBEC (see the Understanding The Chrysler ECU page if you don't know what these are).
If you find the voltage at every place where you saw that wire, then your J2 feed is probably good. Make sure you checked for it at the power module or ASD relay and SMEC/SBEC.
If you couldn't measure it anywhere, then your J2 feed from the ignition switch is bad. Check the wiring and replace the switch if necessary.
If you only measured it in some spots but not others (particularly at the power module, SMEC or SBEC), then you have a bad splice. The J2 splice is actually a series of two or more splices. Usually, two of them are in the harnesses near the battery and fumes from the battery causes them to corrode and break. Consult your wiring diagrams for exact splice locations and repair any bad ones.
Now you need to check the Z1 feed. The Z1 feed supplies power to the ignition coil, fuel pump and fuel injectors. If you have a 1987 or earlier vehicle, the Z1 feed comes right out of the power module (the ASD relay is inside). On later models, the Z1 feed comes from the ASD Relay.
Turn the ignition key to the "on" position.
With the negative probe of your meter grounded to the chassis or negative battery terminal, connect the positive probe to Z1 supply to the ignition coil (may be dark green and may be with a black stripe...consult your wiring diagrams).
Have someone crank the engine while you watch the meter. As the engine is cranked, 12V should appear on the coil.
Repeat the test for the fuel injectors and the fuel pump. Stick the positive probe into the fuel injector connector by the rail to measure there. For the fuel pump, measure the voltage at the fuse panel by pulling the fuse and testing on each of the two contacts.
If you find the voltage at every place where you saw that wire, then your Z1 feed is probably good.
If you only measured it in some spots but not others, then you probably have a bad splice. Consult your wiring diagrams for exact Z1 splice location on your vehicle.
If you couldn't measure it anywhere, then your Z1 feed from the ASD relay is the problem.
Connect the positive probe from your meter to the positive battery terminal and use the negative probe to test the ASD control line. If you have a 1987 or earlier vehicle, this wire leads to the power module (pin 5 of the 12-way connector, dark blue with a yellow stripe). Try to push the probe through the back of the connector into the contact. If you have a later model, you can disconnect the ASD relay and connect the probe there.
Have someone crank the engine. While the engine is cranked, 12V should appear at the relay control line.
If a voltage appeared, then your relay is probably bad, but you may want to check the connections. Verify that the power module or relay is getting the J2 feed and that the Z1 output makes a good connection. If you have a power module, the entire module has to be replaced. If you are good with electronics, the unit can be disassembled and the relay replaced (with some difficulty). Otherwise, just replace the relay.
If no voltage appeared, then it is likely that the computer is not seeing a signal from the ignition reference sensor. You may want to consider replacing it. Be sure that you have good connections at the sensor. The contacts in those two round connectors are prone to getting loose. Be sure that the cables to the sensor are properly secured so that they don't swing around and damage the wires inside.