Chrysler Repair: 97 T&C 3.8 no start, crank sensor, cam sensor

Question
QUESTION: Hi Roland,

This is a follow up question. Van still won't start

My screw up.

I had only been checking for spark on #4 plug, ASSUMING that if one was good they all would be. Today I checked for spark on 2,4 and 6, The easy ones. #2 and 4 had good spark, #6 had no spark until the end of cranking then produced a barely visible tiny orange spark. Continued checking #6 and during 7 cranking cycles it never sparked again. So with all that cranking it only produced one tiny orange spark.

Also when I changed the plugs before all this started that was the plug that was completely covered with fluffy black soot. Not oil, soot. Like it was running rich. But with a weak spark it would only be getting partial combustion making it appear like it was running rich. And causing the original miss that caused me to change the plugs.

I had checked the coil pack earlier and the resistances were with in the spec.

I'm getting 45# fuel pressure and have good compression.

Would you by chance know which pins on the computer plug go to the plug on the coil pack. I'm hoping for a broken wire.

Also before this happened there was a slight delay when I would turn the before the starter would start cranking, about 2 or 3 seconds. Since it broke down that delay is gone. When I turn the key the starter immediately starts cranking. Not sure if that is a clue to something or not.

Thanks,
Rick



(Quote from last question I asked)
Hi Roland,

1997 Chrysler T&C minivan 3.8

Backfiring, missing under load. Engine code: 43 multiple misfires. Changed plugs and wires.
Reset A/C (flashing lights)

Ran fine for 2 days. Going down road at 50 mph, engine quit, not stalled, just quit, I didn't even realize
it had quit running. Would not restart,
Trouble code: 54 no signal from cam sensor.  I didn't check the code until after I had tried to restart it.
Changed cam sensor and crank sensor. Still no start, engine coughs like it wants to start. Had it towed home.

Pulled ASD relay, 12 volts at pin 30. Got engine code: no output voltage from ASD. (this was from when I had the ASD relay out while checking voltage)
Changed ASD relay. (this gave me a spare relay to work with) Pulled dash and resoldered connections on main instrument cluster connector. ( 2 cold solder joints found)
Jumpered fuel pump relay, fuel pump working. Getting 12 volts at fuel injectors. Pulled front spark plugs, getting a weak, orange, erratic spark. Plugs were wet with gas.
Getting 8.8 volts at cam sensor input. Getting 12.65 volts at battery. Getting 10.6 to 11.4 volts at coil pack while cranking. Getting 11.6 volts at battery while cranking.
Checked resistance on coil pack, got 0.80 ohms on the primaries and 12k on the secondaries. The spec for the primaries is 0.45 to 0.65 @ 70 to 80 degrees.
It was 90 degrees. Secondaries spec is 7k to 15.8k.

jumpered the ASD by wrapping a piece of wire around terminal 30 & 87. Those are the pins that short together when the relay is activated. Plugged it back in and tried starting.
No start. But it did set a 42 code: shorted or open ASD....

ANSWER: Hi Rick,
3 and 6 go to pin 2
2 and 5 go to pin 3
1 and 4 go to pin 11
These are from the '98 manual whose controller has two 40-pin plugs.
If your controller has one 60-pin plugs (as in '95) then the pins are 18,17,19 respectively in the same order as above (at least that is how they call out coil driver 3,2, and 1, but don't specify the pistons).
I can't explain the delay unless maybe the voltage on the battery was low, earlier?
Keep up the good sleuthing!
Roland

---------- FOLLOW-UP ----------

QUESTION: This is getting long but I appreciate your assistance.
Roland,

Thanks,
I checked the continuity and it was good from the PCM plug to the coil pack plug.

My VIN says my van is a 97 but it has two 40 pin plugs on the PCM.

I got an LED test light today and hooked it to the coil pack inputs at the 4 connector plug. I should be getting a steady even flash, I'm guessing about 1 a second (250rpm cranking). But all I'm getting is an occasional flash or two, very erratic. When I quit cranking the LED flashes for about a second. This has most likely been what has been giving me the impression it was trying to start.

The crank sensor is new, I left the paper on it. But now I'm wondering if I pushed it in far enough or if it slipped when I tightened it up.

Can I check the sensors with the LED?

I'm at my wits end with this. I did electronics in the Navy but we had all the fancy equipment and everything had tubes in it.

I have to wait another week to get a scan tool.

Any ideas or suggestions? I'm thinking its the computer but can't waste money on one if that isn't the problem.


Answer
Hi Rick,
It would be good to check out the crank sensor signal. The tip of the paper-covered sensor is supposed to be pressed against the flex plate surface and helt there while you tighten its retention bolt. It the test shows it isn't producing reliable voltage pulses then you could remove it and see if the space is still there, and if it has worn away then just buy a new paper spacer at a dealer parts counter and re-install it (or if the paper looks like new then install it again). The test of the sensor would be to put a voltmeter or an LED if that is all you have so long as 5 volts will cause it to light. You would put pins through the insulation of the gray/black and black/light blue wires, then put the voltmeter/LED between the pins. Then put the ignition switch in the run position, and then turn the engine over by hand using a socket and ratchet handle on the crank pulley bolt. The voltage should oscillate between 5 and 0.3V 12 times (three groups of 4 pulses) per revolution of the crank. You could alternatively use the pins on the same wires at pin 32 and 43 of the pcm plugs if those are more accessible. So give that a try and see if you are getting reliable signals.
Roland