No start. Cranks good & strong.
Checking for spark.
All alone here, no one to help me, so I am jumping both the starter relay & the ASD relay, instead of turning the main switch.
Specifics: #30 is jumped to #32, & #60 is jumped to #62.
My test light shows voltage at the green-orange wire at the connection at the coil pack.
Spark plug is hand-held against ground.
Result: no sign of spark.

What gives?

Everything is connected. Crankshaft sensor, etc.

By keying on, and jumping just the starter relay, the ASD should pull in by itself. If the ASD is not pulling in via the PCM, then there is potentially no cam crank sync. If there is no sync, there will never be any spark or injector pulse.

The better thing to check at the coil is the two grounds, to see if the PCM is switching ground on and off. You should be able to do this by back probing the connector with a paperclip, and using a test light. If the PCM is switching ground, and the coil has 12 volts, then possibly the coil got damaged somehow.

Ignition coil number 1 and number 2 drivers. They switch the coils to ground, creating current flow, energizing the coils. when the PCM switches the ground path off, the coil's magnetic field collapses, creating the spark.

Today I tested continuity on all wires for both the crank & cam sensor, & also the coil pack. All have continuity.
The method I used was ohmmeter, with its two probes, one on sensor end, the other on the PCM end. Zero ohms for all.

How can I tell if the coil pack is being energized?
Also I tested for voltage on the crank & cam sensors, but my voltmeter indicated zero volts while the engine was being cranked.
The method I used was voltmeter, with its two probes, one on sensor end, the other on ground end.

Today i ordered a new Ignition Coil Pack.
Update: still no spark, even with the new Ignition Coil Pack.
The coil driver grounds are the pcm ground. That is the one ground point right behind the left headlight. If the pcm is not getting it's ground, it will not be able to provide grounds to the circuits that need them to work.The ground on the control side of the relays are controlled by the pcm. It provides ground to actuate the asd, fuel pump, starter, and other relays.
Update: That ground is intact.
Today my test light remained a steady light while probing both of the two driver wires on the coil pack. This is, rather than the orange wire in the middle.

When I disconnected the wire harness from the coil pack, I probed, with my test light, the two driver wires, and my test light indicated zero voltage for both the two driver wires.

These two driver wires are known as "Coil Negative" and a pulsating light would indicate normal operation. But my test light remained a constant or steady light for both the two driver wires. The coil pack is brand new, so I think i have a driver or transistor problem.

No flicker means no control, on either of the "Coil Negative" or driver wires.

A jumper wire is connecting the dark green & orange wire with the B+ wire.

Today I checked the ASD relay and the fuel pump relay.

When i set a jumper wire from ground to the brown wire that runs from the ASD relay to the PCM., which the fuel pump relay clicked like mad, and the fuel pump sounded up, pressurizing the fuel.

The ASD relay sounded off clicking when i set a jumper wire from ground to the blue & yellow wire that runs from the ASD relay to the PCM. This caused the green & orange wire to go live to the ignition coils.

Also I ordered a used PCM on Ebay. Maybe i fried my PCM by disconnecting or installing it with the battery still connected?

I think PCM's are more durable than that. You aren't supposed to disconnect the battery with the ignition on, but I think they can hold up to even that. If the key wasn't on, I highly doubt that may be the case.
Update: still no spark, even with the new PCM that i ordered off EBay.


Tested the green & orange wire for voltage with my test light, at the ASD relay, & at the ignition coils.

Fuel pump still does not get power when ignition key turned to run.

Also, the Tach or RPM gauge shows zero activity. The crank sensor is secured in position, & connected to harness.

Wish this car had an ignition module that was separate from the PCM. Easy to test. A PCM has a bunch of inputs from sensors,
so it is complicated.

My focus is now on the crank sensor, & this is a good thread.
viewtopic.php?f=1&t=397376

The PCM is failing to energize both the ASD & the Fuel pump relays, when the ignition key turned to the On position.

Update: all fuses are good.
Relays both have voltage on both leads.
The DG/OR wire has good continuity from ASD Relay to PCM.
Fuse #10 for Engine Ignition Feed should get voltage when ignition switch is in either Run or Start.


cut-and-pasted:

When trying to start car I have no CEL, no fuel pump.
Key dance does nothing.
No SKIS.
With key in start position I have power to all ignition switch wires (except key sense ground).
PCM connectors C1 and C2 have constant power to pin 46 and with key in run position, power to pin 20.
Grounds on PCM connectors C1 and C2 (pins 10, 47 and 50) test good.
I can force the fuel pump to run by grounding leg 63 (the leg the PCM should ground) on fuel pump relay with key on.
Grounding leg 38 on ASD relay makes it click on. (key on)
I can force the car to crank over by grounding leg 28 on starter relay and turning key to start position.

Grounding all 3 I can get in and crank the car over with fuel pump running (constant) but no start with or without PCM (C1 and C2) connected.
Why is this?
The PCM is failing to energize the fuel pump relay, when the ignition key turned to the On position.
Swapped relays, no luck.

What input does the PCM need to energize the fuel pump relay?

Battery voltage is present at both leads to the fuel pump relay.
That means both fuses #10 & #21 are good.
'95 and '96 had plastic crank sensors. They were prone to failure and seldom threw a code. Have you tried replacing to a newer version? You can use any junkyard Chrysler 4 cylinder sensor up to 2002. Get the pigtail also. Stay away from Chinese knockoffs. If a PCM doesn't see a crank sensor signal, there will be no spark.
But the PCM energizes the fuel pump relay upon turning on ignition switch, and that should happen with or without the crank sensor.

am i right? wrong?
My voltmeter shows zero volts here at the PCM connector, pin #46. Traced wire to data link connector.
how can it have constant power?

Also tested for ground at pins #10, 47, & 50. All show good ground.

The orange wire shows about 2.2 volts for reference voltage on both cam & crank sensors. Shows same at PCM, so low reference voltage not due to voltage drop. should be 8.0 volts with ign key on.

The Manifold Pressure & Throttle Position sensors both are getting about 2.4 volts for reference voltage.

Also note: connectors for both cam & crank sensors are identical, with same color wires.
My fuel pump is good, in fact it primes whenever i ground the fuel pump relay, by inserting my test light into the relay, where
the brown wire comes from the PCM.

When I turn to key to On without cranking, i should hear the fuel pump. But i don't.

The green & white wire coming from the fuel pump relay to the fuel pump does not get voltage.

Also i have installed one of two PCMs that i ordered last week. They must be good?
Tachometer still shows no activity while cranking.

 

Have you tried back probing all the connections with them connected and powered? Your meter may show continuity and zero ohms between the ends of the wires, but if the wire is partially corroded, cut, or shorted somewhere you won't find it that way. It's burned me a few times...

I'm thinking since you have to manually engage the ASD relay instead of the PCM it's probably not going to create any signals to generate spark, fuel, etc since it's not telling the ASD relay to turn on in the first place.

The only other thing I can think of keep checking grounds. Have tried to measure a voltage drop between your battery ground and other ground points? It's not doing enough strange stuff to be in the main, but maybe a ground from a central point to your PCM could use another look.

 

Do you have any codes or is the CEL on?
Have you load tested the power and ground wires to your PCM?
How many wires on CKP AND CMP sensors. I dont have a diagram to refer to at the moment. I can come back to that.

 

First thing I would be checking ,is Crank sensor signal at the ECU. I use a cheap DSO138 Dig Oscilloscope. Picture of my Mazda 323 Crank sensor at cranking speed. No signal, no spark or injector pulses. Fuel pump relays are normaly run for a few seconds by the ECU then look for Crank pulses or ign pulses to keep the relay energized..

 

First thing I would be checking ,is Crank sensor signal at the ECU. I use a cheap DSO138 Dig Oscilloscope. Picture of my Mazda 323 Crank sensor at cranking speed. No signal, no spark or injector pulses. Fuel pump relays are normaly run for a few seconds by the ECU then look for Crank pulses or ign pulses to keep the relay energized..View attachment 160647

Hi debe
Thanks, i just now ordered this:
https://www.ebay.com/itm/142642969949

 

Do you have any codes or is the CEL on?
Have you load tested the power and ground wires to your PCM?
How many wires on CKP AND CMP sensors. I dont have a diagram to refer to at the moment. I can come back to that.

Hi bwilliams60,
the CKP AND CMP sensors have three wires each, see uploaded file for schematic.
Yes, I load tested the power to the PCM, which gets gets battery voltage on PIN #46, see uploaded file for schematic "8 PCM pin-out."
But this power was interrupted due to a wire breaking on me, which i fixed, see uploaded file " code reader."
My code reader could not get codes, or even light up. The same wire feeds the data link interface, & it runs from
the relay center.
Yes, I load tested the ground wires, by checking for continuity and near-zero ohms between the PCM PINs #10, 47, & 50, and chassis ground, see uploaded file "ground."

 

Have you tried back probing all the connections with them connected and powered? Your meter may show continuity and zero ohms between the ends of the wires, but if the wire is partially corroded, cut, or shorted somewhere you won't find it that way. It's burned me a few times...

Hi geekoftheweek,
good idea, let me do that today.

 

Do you have any codes or is the CEL on?

Yes, see the three uploaded files. All I have are three codes.

 

What scan tool are you using? Does it have the NO START monitor feature? If it does, what is the CMP and CKP state when you first turn the key on? If you do not have this feature I would check both sensors for 8V reference and ground. You can test between them with an incandescent test light. If that is okay, connect your LED test light to ground and backprobe the CKP and CMP signal wires while backprobing. They may flash a pulse while it cranks. My money is on one of them being at fault if what you have stated above is all correct. The scope will tell you for sure. You can also get a cheap adaptor for your cellphone to turn it into an oscilloscope. Works great.

Just one quick question. When you turn the key on, is ASD and fuel pump relay energized for one second or not at all? Us eDVOM to check.

 

What scan tool are you using?

it is a cheap Code Reader from Harbor Freight. mine is ten years old, not sold anymore.
https://www.harborfreight.com/zr4-obd2-code-reader-63808.html

What scan tool are you using? Does it have the NO START monitor feature? If it does, what is the CMP and CKP state when you first turn the key on? If you do not have this feature I would check both sensors for 8V reference and ground.

You can test between them with an incandescent test light. If that is okay, connect your LED test light to ground and backprobe the CKP and CMP signal wires while backprobing. They may flash a pulse while it cranks. My money is on one of them being at fault if what you have stated above is all correct. The scope will tell you for sure. You can also get a cheap adaptor for your cellphone to turn it into an oscilloscope. Works great.

Just one quick question. When you turn the key on, is ASD and fuel pump relay energized for one second or not at all? Us eDVOM to check.

Hi,
the ASD and fuel pump relay would not energize when i turn the key on.
Also i tested for both sensors for 8V reference, got only two volts on the orange wire.

 

Update: today i got spark. The ASD and fuel pump relay now both energize when i turn the key to run position.

My old PCM is being used. Proves i wasted my $$ buying those new PCMs.
All i did was follow this advice from the poster named geekoftheweek:

geekoftheweek said: ↑

Have you tried back probing all the connections with them connected and powered? Your meter may show continuity and zero ohms between the ends of the wires, but if the wire is partially corroded, cut, or shorted somewhere you won't find it that way. It's burned me a few times...

Focused on the cam sensor, i tested continuity on the three wires. Then I noticed that the orange wire had proven continuity to the PCM chassis ground, but only when powered, or with the key to run position; also I switched the ground to battery, got same result. But with the key to off position, the orange wire had zero continuity to the PCM chassis & battery grounds. This is abnormal, why would the orange wire ever have continuity to ground?


Repeated the test with the black & light blue wire. Normal operation, has proven continuity to the PCM chassis ground.

The test with the tan & yellow wire is when things got weird. When testing for continuity to the PCM chassis ground, which makes no sense
as the tan & yellow wire goes directly to Pin #33 on the PCM, i proved continuity to the PCM chassis ground, and at this moment i heard clicking sounds from the relays, and the fuel pump working. Startled me so much, I just had to feel the relays with my fingers while repeating the test. Yup, both the ASD and fuel pump relay were being grounded.

Grabbed my incandescent test light and probed the green & orange wire on the coil pack connector, and the test light lit up for a second upon my turning the key to the run position.

 

One lesson I learned - the hard way - was that wire testing with a meter can miss things. A meter has a very high impedance, at least 1MΩ and usually more, so a tiny current is all it takes to show continuity.

Like you, I was struggling with a no-start condition and had bought a PCM that didn't solve my problem. I finally decided to retest some of the harness wires using the old battery and lightbulb method. The lightbulb, unlike the meter, needs an amp or so to light up. I was reluctant to use this method because it applies ground or +12V to places that may or may not be designed for that, if you don't know what you're doing (like me) or are just simply sloppy.

But after careful research and preparation I ran my tests and discovered that a wire that had passed continuity with my meter would NOT pass enough current to light the bulb. A little inspection under the car (where the harness passes) revealed a nick in the insulation and a bulge. Salt had gotten in and the wire corroded away inside the insulation.

This project was 99% diagnosis and 1% repair.

 

This project was 99% diagnosis and 1% repair.

Most of electrical problems on vehicle fall under this category. Proper diagnostic techniques always find the right answers. That is why I asked earlier if he load tested power and ground to PCM. This can be done as easily as a light bulb or blowing a low amperage fuse across them.

I think he is heading towards a bad CKP sensor or CMP sensor. Money on the first one. If PCM is powering up fuel and ASD, it is waiting for those two signals to come in.

 

I think he is heading towards a bad CKP sensor or CMP sensor.


how so, if i have spark? seems i have a short to ground.

 

Sorry, must have missed the part where you have spark? Does it run now?

 

Focused on the cam sensor, i tested continuity on the three wires. Then I noticed that the orange wire had proven continuity to the PCM chassis ground, but only when powered, or with the key to run position; also I switched the ground to battery, got same result. But with the key to off position, the orange wire had zero continuity to the PCM chassis & battery grounds.

Looking at your diagram it seems the orange wire should have 8 volts not ground. I would find S123 in the crank sensor diagram and see if that connection is coming apart.

I've seen in my line of work where the convoluted tubing the harness is in can wear through the insulation of wires where it bends and such if it moves around a lot. It usually takes at least a couple or three or for hundred thousand miles to happen so it's kind of a long shot in your case I would assume, but maybe something to look in to.

 

Another thought... what happens when you connect pins 1 and 3 on your coolant temp sensor connector? I should make the dash gauge peg on the hot side if I'm reading the diagram right. That may tell you if you have a sensor ground issue.

 

Yet another thought... If your harness is held in place by plastic zip ties you may want to look at those points also. They can manage to rub the insulation off of wires too over time. I'm kind of getting the feeling since it worked for a moment that it may be a wiring issue and you just bumped the right location in the harness to get it to go.

 

Another thought... what happens when you connect pins 1 and 3 on your coolant temp sensor connector? I should make the dash gauge peg on the hot side if I'm reading the diagram right. That may tell you if you have a sensor ground issue.

Let me go try that.
u mean, place a jumper wire between pins 1 and 3?

 

Yet another thought... If your harness is held in place by plastic zip ties you may want to look at those points also. They can manage to rub the insulation off of wires too over time. I'm kind of getting the feeling since it worked for a moment that it may be a wiring issue and you just bumped the right location in the harness to get it to go.

No zip ties; all wires were hanging loose. But now I wrapped them in tape.