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Dan M
Dodge Dakota
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12/29/2005
10:03:08
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 Subject: no start, no spark at coil output
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I got into my truck last night, backed out of the garage. Left the truck running, hopped out to close the garage door. The truck died and would not restart. I tested the ASD and fuel pump relay and they tested fine.
I pulled the secondary ignition cable from the top of the coil and pulled in my in-line spark tester (king with light) and truck started up fine. I removed spark tester and truck started up fine. I parked the truck beside the house.
Later, I went to start my truck and it would not start. Plugged in my spark tester on top of the coil again, it started up then immediately died. I tried starting again, no start and light did not light up. This is a new coil I installed a few weeks ago. I took it back to parts store to replace it thinking it was bad.
Got home, installed new coil. Truck would not start. Connected spark tester and light would not light up. I am pretty sure both coils are not bad.
I did not have time last night to test further.
I am going to test electrical connector at the coil. I am guessing that the voltage will be low. I found that 1 wire splices into the ASD relay, the injectors and the oxygen sensor. The other wire goes to PCM. I am hoping for a bad wire or splice and not Bad PCM.
Anyone else experience something similar?
95 3.9L auto.
- Dan M
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davec
Dodge Dakota
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12/29/2005
16:06:33
| RE: no start, no spark at coil output
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I can't be certain but I seem to remember that they ran the wiring harness underneath the battery on these trucks. I know I had some problems with earlier 90's models where the harness would corrode due to battery acid. I'm not sure if this would apply in your case. The problems I experienced was with the battery on the driver's side inner fender and the harness ran right underneath it. The few instances I remember where starting problems.
dave
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Dan M
Dodge Dakota
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12/29/2005
16:11:09
| RE: no start, no spark at coil output
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the PDC sits right beside/behind the battery.
The splice for the ASD/injectors/PDC is on the drivers side engine between the block and the valve cover.
I do have an alldatadiy subscription and the wiring/splice diagrams are priceless.
I found a no-start test procedure today. I'm running through that now. I'm up to where i need to test the ASD relay from the PDC perspective (relay's themselves pass) if that passes then I need to test the wiring between the PDC and the coil and the coil and the PCM.
- Dan M
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Dan M
Dodge Dakota
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12/29/2005
20:44:38
| RE: no start, no spark at coil output
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following the instructions on alldatadiy I jumpered relays to the ASD socket. I tested the relays using my DMM (ohm) and all 4 tested bad?? That seems a little odd to me.
4 relays are for ASD, fuel pump, starter and A/C clutch. Just as a sanity check, I was going to purchase a couple of new relays. Pepboys/Advance/Autozone/Oreilly's could not find any information. I did find the relays on napa's website, unfortunately they are closed. I will have to try to pick those up tomorrow.
My battery tests at 12.5V. I believe the starter is working cause the engine cranks. I beleive the alternator is working because my battery has not gotten any weaker in the last couple of days.
I was going to test the wiring to the coil but could not as it requires the ASD relay be working and I could not get my relays to pass the relay test.
- Dan M
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mattleg
Dodge Dakota
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12/29/2005
20:57:00
| RE: no start, no spark at coil output
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You tested the starter relay and it tested bad, yet the engine cranks, so your probably not doing the test right.
GP Sorensen #41-5612 is the relay thats suppose to work. I think there actually for fords, but they work fine.
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Dan M
Dodge Dakota
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12/30/2005
06:31:13
| RE: no start, no spark at coil output
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I just looked up that part number and it is not the same relay I have. The pins are wrong according to the picture.
I am sure I did the test right but the wiring for the ASD in the pdc may be bad. In doing this test it is supposed to open the relay which I should then get continuity between 2 pins that have no continuity when the relay is closed.
- Dan M
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davec
Dodge Dakota
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12/30/2005
08:34:30
| RE: no start, no spark at coil output
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Sounds like a wiring problem to me. I highly doubt you have 4 bad relays. Better reread that diag. procedure and do it over again. You missed something somewhere along the line. Anytime you get something funny like 4 bad relays, it's time to go back to the beginning. Recheck it again and get back to us.
dave
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Dan M
Dodge Dakota
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12/30/2005
10:26:41
| RE: no start, no spark at coil output
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One of the relays tested on the border line so I'm going to go ahead and pick up one on my way home today.
I will redo the test again. I will test the wiring, it should be faily easiy to do. I should be able to test from the PDC cavity to the coil. I am thinking the splice is going bad.
- Dan M
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Dan M
Dodge Dakota
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12/30/2005
20:59:06
| RE: no start, no spark at coil output
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I picked up another relay. Put it in, no start. Started checking the wiring from ASD to injectors and coil. Tested fine. Tested coil fine. Plugged coil wire into coil and unpluged the cap end, tested for spark on ground, spark tested fine.
put cable back on cap, took a couple tries but truck started up. Turned off and back on several times, started up fine every time.
One thing I noticed, with engine running if I drop hood down (let fall from a foot up so that it latches) truck dies if it's running. But starts up fine. Anyone else ran into this issue? I am guessing loose ground.
new cap and rotor, new plug wires (as of a few weeks ago troubleshooting backfiring issue). And new coil too.
Very odd! Why me?!
- Dan M
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OBIO3
Dodge Dakota
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12/31/2005
16:17:58
| RE: no start, no spark at coil output
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My guess is while you was doing this you wiggled a loose or bad wire > Think the hood answered your problem >
So many problems > So little time
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Dan M
Dodge Dakota
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12/31/2005
20:45:45
| RE: no start, no spark at coil output
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It's not a loose plug wire. I dont think it's a bad wire between injectors, oxygen sensor and asd. I will start checking the grounds tomorrow after I finish installing my new brakes pads on the front. One side down, one to go.
- Dan M
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Dan M
Dodge Dakota
JOIN HERE
1/01/2006
10:31:49
| RE: no start, no spark at coil output
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Went to pull truck out of garage so wife can park her car in. Backed down the driveway to give her enough room. While truck was running and in drive with brake applied and sitting on hill (back end lower than front end) truck died. Would not start. Tried several times. Plugged in-line spark tester on top of coil, light did not come on when engine cranked. Removed inline tester, plugged wire back on top of coil, removed other end from cap. Held against ground on firewall, first few cranks of the engine I got no spark then I got spark. Put wire back on cap, truck started up fine.
Not knowing much about electrical systems I have a few questions based on the above.
The ASD relay is good. Battery is good. According to wiring diagrams, battery feed goes to PDC. The ASD in the PDC is wired to all 6 injectors, the oxygen sensor and the coil. The coil is grounded to a pin in the PCM.
I guess the next steps would be to check the coil ground wire at the PCM (pin 19 if I recall correctly).
Questions I have that I hope one of you can answer:
1) could a bad ground at pcm cause a no spark condition at the coil? (I will test the ground wire with my DMM).
2) Could a bad cap cause a no spark condition at the coil? (I have my original cap still, i replaced it a few months ago when I was troubleshooting my backfiring issue).
Both the coil and cap (and rotor and distributor pickup) are new. Also, when I took my truck to shop after being unable to find root cause of backfiring, they told me coil was weak. I am not sure how they tested it. I did a ohm test on my old coil and the resistance was greater (but not by much) than new coil. Old coil was 12.9 and the new one is 12.5. According to alldata, the resistance should be < 15.
- Dan M
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Dan M
Dodge Dakota
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1/01/2006
15:58:38
| RE: no start, no spark at coil output
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problem found! working on fix
pins 11 and 12 at pcm are grounds. pin 12 is loose. When i drop the hood the pcm connector shakes and ground is lost and engine cuts off.
when engine running, i can tap the pcm connector and engine cuts out.
I used my DMM in audible mode and tested pins 11 and 12, jiggled 11, no lose of signal. Jiggled pin 12 and get lose signal.
- Dan M
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Dan M
Dodge Dakota
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1/01/2006
16:19:21
| RE: no start, no spark at coil output
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according to guy at advance, I need to get a new pcm connector. They have no tools to repunch the wiring inside.
called napa, guy said he didn't know much about pcm connector wiring but said any "advanced repair shop" has new connectors and can replace it for me. They do not sell those connectors. Called another napa store who said those connectors have a locking mechanism and that dealer should be able to put a new one in (do not need a new pcm connector).
Called pepboys service who said they can't do that work that i need to go to a dealer.
I will call the shop I use tomorrow , not sure if they will be open or closed.
- Dan M
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mattleg
Dodge Dakota
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1/01/2006
16:58:17
| RE: no start, no spark at coil output
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Good work finding the problem. Tracking down wiring problems is hard and frustrating.
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OBIO3
Dodge Dakota
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1/01/2006
17:10:46
| RE: no start, no spark at coil output
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Don't know how dificult this lose pin is to get at but one possibility is using a soldering iron > Put solder on iron and then rub it on he pin > should fatten it up a bit to make a tight fit > I've used this trick many times over the years on all sorts of things with 100% seccess >
So many problems > So little time
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Dan M
Dodge Dakota
JOIN HERE
1/01/2006
20:11:49
| RE: no start, no spark at coil output
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It's not the pin itself that is bad. The PCM connector has all of the wiring go into it. The PCM has pins which the connector fits over. I would have to build up the wiring so it fits snug into the connector slot. Not sure how easy that would be. One thought was the turn the engine on, shove the wire in as far as it would go and super glue the wire to the connector. should not get lose or jiggle. If the engine cuts off, i know it's not right.
I will call shop and dealer tomorrow and hope one is open for me to talk to.
I would have to pull the wire out of the PCM connector. I am not sure how it "locks" into place so it can't be pulled out.
thanks for the tip. sounds like a good trick to keep in my head.
- Dan M
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zzark
Gen II
1/01/2006
22:57:46
| RE: no start, no spark at coil output
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Is it the male or female that is loose?
Or, is it on the PCM or the connector?
zzark
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OBIO3
Dodge Dakota
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1/01/2006
23:10:07
| RE: no start, no spark at coil output
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With the problems your having finding one the junk yard might be a reasonable choice >
So many problems > So little time
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Dan M
Dodge Dakota
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1/02/2006
08:22:13
| RE: no start, no spark at coil output
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The PCM is fine. It has the male pins which slide into the front side of the female cavities. The wiring which runs to the various electrical components of the engine slide into the back side of the female connector. There has to be some sort of locking mechanism in the connector which holds the wiring in place or else it will fall out.
Compare it to the electrial connector of the TPS. The TPS bolts in to the TB (same as the PCM wiring connector, has a single bolt that screws into the PCM). The TPS has pins same as the PCM. The wire harness that connects to the TPS has female cavities, same as the PCM wiring connector. Then on the backside, the wires on the connector slide and lock into place on the connector. Same as the PCM wiring connector.
- Dan M
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Rustywrenches
Dodge Dakota
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1/02/2006
12:21:31
| RE: no start, no spark at coil output
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Can you try jumping past the plug - just hard wire together the offending male and female?
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