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Re: Car starts when key is RELEASED, why? *UPDATE* [Re: MONC] #1077434
09/24/11 07:44 PM
09/24/11 07:44 PM
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Strawdawg Offline
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well, that tells you the coil is getting voltage in the start position, but, I would have thought it should get over ten volts...have you tried charging up the battery? It should have read more than 13 while running if the alternator is doing its job and the battery is healthy...imo, anyway

Unless there is a big drop in the bulkhead connector, but, normally, if the battery reads 12 volts, it is basically discharged.

Also, have you checked the gap in the distributor to make sure it is close to .008". I noticed my car does not like to start on a weak battery if the gap is too large

Last edited by Strawdawg; 09/24/11 08:02 PM.

Steve
Re: Car starts when key is RELEASED, why? *UPDATE* [Re: Strawdawg] #1077435
09/24/11 09:28 PM
09/24/11 09:28 PM
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I am trickle charging the battery now.
Will check tomorrow if it doesn't rain.

I will check the gap tomorrow as well, thanks.

Re: Car starts when key is RELEASED, why? *UPDATE* [Re: MONC] #1077436
09/24/11 10:03 PM
09/24/11 10:03 PM
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If the charging circuit is stock the voltage you are reading at idle is probably correct , mopar altenators of that era don't jump to 14ish volts till about 1400 rpm ... i think that is the rpm i have seen posted .

You should have something close to battery voltage at the coil when starting , you have something somewhere that is not maikng a good connection and has some resistance. How are your connectors from the column to the dash harness ?

Re: Car starts when key is RELEASED, why? *UPDATE* [Re: MONC] #1077437
09/24/11 10:14 PM
09/24/11 10:14 PM
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Back in the day, my buddy had a Dart Sport 340 that did the same thing. Crank it's guts out....release the key and it would start. It ended up being the pickup module in the distributor. Fast forward to around 1989. I had a Dart Swinger with a 318, and it started doing the same thing. I replaced the pickup and star wheel in the distributor and it fixed it. Try replacing those parts, and use a brass feeler guage to set the gap. Good luck.

Re: Car starts when key is RELEASED, why? *UPDATE* [Re: JohnRR] #1077438
09/24/11 10:27 PM
09/24/11 10:27 PM
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Quote:

If the charging circuit is stock the voltage you are reading at idle is probably correct , mopar altenators of that era don't jump to 14ish volts till about 1400 rpm ... i think that is the rpm i have seen posted .

You should have something close to battery voltage at the coil when starting , you have something somewhere that is not maikng a good connection and has some resistance. How are your connectors from the column to the dash harness ?




you can prove the point by putting a jumper from the battery to the coil, and then, hit the key. If it cranks right up, it is a voltage loss problem as suspected. Go ahead and get the battery charged up to eliminate that possibility and check the gap as well, but, like he said, you should be reading within a couple-three tenths of the battery voltage at the coil...the drop will get bigger with load in most cases.


Steve
Re: Car starts when key is RELEASED, why? *UPDATE* [Re: Strawdawg] #1077439
09/25/11 04:37 PM
09/25/11 04:37 PM
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Ok I tried using a jumper from the positive terminal on battery to the positive on the coil. Then tried starting it.

Same result. Kept cranking in start position and started when it was back in run ( released the key).

I tried switching to a newer battery ( < 1yr old) , same result.

I will have to get some brass feeler gauges ( thought I had some) to check the gap on the electronic pick up.

What's involved in changed the "star wheel" as mentioned above , or do I have to replace the whole distributor?

Re: Car starts when key is RELEASED, why? *UPDATE* [Re: JohnRR] #1077440
09/25/11 08:08 PM
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Quote:

You should have something close to battery voltage at the coil when starting...

I had about 12 volts at coil when using jumper from battery and it still had the same issue.

... How are your connectors from the column to the dash harness ?

I changed the ignition switch last week, and cleaned the connections as well cleaned the connections at the bulk head .






Re: Car starts when key is RELEASED, why? *UPDATE* [Re: MONC] #1077441
09/26/11 12:41 AM
09/26/11 12:41 AM
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4 pin ECU I am assuming? Might sound off the wall but going by the descrip and not being able to visual check it, if gapping the reluctor to .008" w a brass feeler gauge is not it me I'd cut the wire to the coil positive primary and cut the wire to the "point" of the ECU pentastar connector and jump 12V directly to both of them from the batt positive post then crank it from the starter relay. The ECU/coil/pickup are good and the ECU is grounded as it "runs" and the pickup gap may need reducing & that only leaves something in the wiring grounded/open when in ign2 "crank" unless we're still missing something and we very well may be but this is what I'd try


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Re: Car starts when key is RELEASED, why? *UPDATE* [Re: RapidRobert] #1077442
09/26/11 12:46 AM
09/26/11 12:46 AM
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yes....this has to be something very simple that we are missing....


Steve
Re: Car starts when key is RELEASED, why? *UPDATE* [Re: MONC] #1077443
09/26/11 07:41 AM
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Quote:

Ok I tried using a jumper from the positive terminal on battery to the positive on the coil. Then tried starting it.

Same result. Kept cranking in start position and started when it was back in run ( released the key).

I tried switching to a newer battery ( < 1yr old) , same result.

I will have to get some brass feeler gauges ( thought I had some) to check the gap on the electronic pick up.

What's involved in changed the "star wheel" as mentioned above , or do I have to replace the whole distributor?




OK, by putting on that jumper wire you by-passed all your harness and ign switch . I thinks its in the ecm and that its not being powered when your in start position .
I know some of the guys can tell you which pin needs to be powered while cranking or just check the ecm pics somebody posted earlier .

Re: Car starts when key is RELEASED, why? * UPDATE* [Re: MONC] #1077444
09/26/11 07:50 AM
09/26/11 07:50 AM
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Had the same thing many years ago, had to take it in since I knew nothing about electrical. The mechanic at the shop, a good friend, said it was the electronic ignition "brain box".


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Re: Car starts when key is RELEASED, why? * UPDATE* [Re: cdstl] #1077445
09/26/11 10:44 AM
09/26/11 10:44 AM
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I was thinking about this last night. If I recall, you checked for power on the brown wire coming from the ignition switch under the dash when the key is in the start position, and you verified that it had power there, had power under the hood all the way to the coil.

The only thing that looked strange to me was that you said this wire only had 8.5 volts at the coil when cranking and that the battery (at that particular time) was reading 12 volts.

Looking at those numbers, it appeared to me that the battery was discharged as it should be around 12.4 fully charged and the voltage at the coil (when the engine is being cranked) should be close to 11 volts.

Or, if not discharged, there was a big voltage drop between the battery and the coil in the wiring which is not uncommon in these old bulkhead connectors or ignition switches....that is the reason we check the voltage along the path to see if we can isolate a spot where it suddenly changes...like between the brown wire under the dash and on the underhood side.

Finally, if the problem was not the battery, or the wiring, yet the voltage dropped so much, it left me wondering if the starter was on the way out and was pulling a tremendous amount of amps which would cause the battery to be unable to maintain the voltage and let it drop to the 8.5 volts that you read at the coil while cranking.

When you jumped from the battery plus straight to the coil, you eliminated the wiring potential problem. Assuming that the new battery was charged, that should have eliminated the battery being the problem.

Now, the unknown factor (to me) is the relationship of the brown wire to the ignition control module. On a car with a four pin ballast and a five wire control module, the brown wire directly feeds the coil but it does backfeed thru the ballast to the control module thru the green/red wire.

On the newer four wire modules, I have not checked to see which wire has been removed, but, I am wondering if those that are suggesting that the module may be the problem are correct.

At this point, I remember why I initially went to the GM HEI module and eliminated all this mess when I bought my car

If it is not the module, then I would try one more thing to see if the starter is the culprit. Disconnect the brown wire from coil +. Take your other battery, connect its plus to the coil plus and connect the battery negative to your engine for the ground...and try to start the car. If it starts then, it has shown the starter current problem to be the problem. If not, I guess we find another drawing board Cars, you gotta love 'em!


Steve
Re: Car starts when key is RELEASED, why? * UPDATE* [Re: Strawdawg] #1077446
09/26/11 12:20 PM
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It does look like, from what I can read, that the older modules, with five wires, do receive their power via the four pin ballast and brown wire while the key is in the Start position...so it is quite probable that either that side of the ballast is bad, or the module is bad.

The four wire modules have the resistor built in the box if I read correctly.

It's very possible we have been going in circles barking up the wrong tree...but, I still want to know why the voltage is so low to to the coil during cranking Maybe the module is shorted internally and taking power to ground?


Steve
Re: Car starts when key is RELEASED, why? * UPDATE* [Re: Strawdawg] #1077447
09/26/11 12:38 PM
09/26/11 12:38 PM
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a 5 pin ECU which requires a 4 terminal (dual) ballast, 2 pins on the ECU need fire in start. one side of the ballast has a nominal .5 ohms and the other 5 ohms and a high mileage one I checked recently had 1.6 ohms and 6 ohms respectively

Last edited by RapidRobert; 09/26/11 12:43 PM.

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Re: Car starts when key is RELEASED, why? * UPDATE* [Re: RapidRobert] #1077448
09/26/11 01:21 PM
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I appreciate all the suggestions, and feedback.
Some reminders though:

I already changed the ECU and the ballast resistor, along with coil, starter relay and didn't resolve the issue.

The ballast resistor is a TWO prong not FOUR , always has been, even before I had this issue.

Re: Car starts when key is RELEASED, why? * UPDATE* [Re: MONC] #1077449
09/26/11 01:30 PM
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OK, check the reluctor gap & might disconnect the wires & jump the 2 circuits (coil/ecu). We're getting closer


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Re: Car starts when key is RELEASED, why? * UPDATE* [Re: MONC] #1077450
09/26/11 02:20 PM
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sorry! I should have gone back and read thru the thread...getting too old and was already lazy!

You might try my suggestion of jumping the coil off a separate battery to eliminate excessive starter drain, circuit problems, etc. after checking the gap


Steve
Re: Car starts when key is RELEASED, why? * UPDATE* [Re: Strawdawg] #1077451
09/26/11 02:57 PM
09/26/11 02:57 PM
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okay, to pause and think about this...

we are assuming that the new module is good which may be a bit risky these days as we see reports of people buying new ones and they not working, but, we would like to assume it is.

Then, the voltage seems low that is going to the coil and to the module (at least it seems low to me).

I am not sure how much voltage the module needs to begin operating but perhaps we need to hot wire the module as well as the coil from a separate battery to make sure that is not the problem?

What do you think, Robert?


Steve
Re: Car starts when key is RELEASED, why? * UPDATE* [Re: Strawdawg] #1077452
09/26/11 05:39 PM
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the 4 pin ECU (that ran at one time) has been switched out to another 4 pinner right? I'd disconnect the hot lead to the "point" of the ECU pentastar connector and disconnect ALL leads off of the coil primary terminals then jump 12V to the coil positive primary and to the "point" of the ECU pentastar connector and reconnect the 1 wire (that you just took off) from the coil negative primary to the appropriate ECU pin then crank it with or without the key. It must start! Oh dont forget to check the reluctor gap and a quick visual for any damage (teeth etc)while you have the rotor out adjusting the gap. yes he could try another battery or jump from another one with cables just like a regular jump start and if his batt has a bad cell it could be dropping voltage fast when cranking but I am a k.i.s.s. guy but we are running out of ideas & sometimes off the wall stuff does happen (part of Murphy's law) and yes I agree the voltage is going to go way up when the starter is disengaged.

Last edited by RapidRobert; 09/26/11 06:05 PM.

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Re: Car starts when key is RELEASED, why? * UPDATE* [Re: RapidRobert] #1077453
09/26/11 06:51 PM
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sounds like a plan to me better to not change too many things at a time. If it does not start this way, then a separate battery could be used to prove/disprove the problem with the voltage, I think.

Last edited by Strawdawg; 09/26/11 07:02 PM.
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