Totally stumped with startup issue

[Terry S]

Ok everyone, i'm a new poster here but I have a tough question:

2000 Dodge Neon. Car starts when the vehicle is cold, drives around totally normal, but if you turn it off when its at operating temperature, the car refuses to start back up. All accessories, headlights, interior lights still work, but the starter doesn't make a sound.

Its a new battery (2 months old), new starter, new alternator. Battery has full charge and putting out appropriate voltage. There is continuity between starter and battery (both negative and positive sides). Voltage is in spec. Starter relay clicks when energized and shows continuity between appropriate pins. All bolts are secure but not over tight. Starter and alternator have been tested off the car as working.

If you can figure this out, you are an automotive god and earn my eternal gratitude and respect

Thanks in advance,
(Stuck in his driveway) Terry

[public]

When attempting to start does the engine turn over? Or is the clicking of the relay all you get?

[foureyedbuzzard]

Originally Posted by Terry S

starter doesn't make a sound.
Starter relay clicks when energized and shows continuity between appropriate pins. All bolts are secure but not over tight. Starter and alternator have been tested off the car as working.

Gut reaction - you have a poor connection somewhere from the engine to the battery NEG terminal. Look at the connection lug for the engine "ground strap" on the engine itself. If it is not absolutely clean AND tight, when the motor gets hot the bolt expands very slightly lengthwise causing the loss of a good mechanical connection. The connection will "work" again after the motor cools and the bolt shrinks.

The continuity test means little due to the high current draw of the starter motor. You can't rely on a VOM resistance reading to prove the integrity of the connections. The VOM puts out < 3 volts and the current is a few milliamps - not enough to mimic the instantaneous heating of the connection present during starting.
While trying to start the car, take voltage readings starting at the starter motor itself. If possible, use a long test lead for the NEG connection and hook it directly to the battery post terminal. This eliminates any connection problems in the engine to ground connection while troubleshooting. If you have full voltage at the starter, check the voltage from starter to the engine itself. If lower, look for a bad connection in the motor to "ground strap" cable. Otherwise keep working back from the starter towards the battery until you find the problem. Don't overlook battery terminals and connecors, etc. Hope this helps

[Terry S]

With the PCM box lid off I can hear the relay's clicking when the key is turned to the on position. The starter doesn't make a sound.

I'll try testing the voltage readings when the key is turned to the start position.

This problem is really driving me nuts and I have a dealership saying that if its the PCM thats bad (I really doubt this), then it'll cost around 1400 bucks. Merry Christmas.

I'll look for the grounding spot on the engine. Not sure off hand where it is, but I'll figure it out. Thanks for your help, and any additional comments greatly appreciated!

Terry S

[public]

Ditto Foureyedbuzzard. I would also clamp a volt meter on the starter and hit the key to see if it is getting current. I recall a starter some years ago that did this. It had the wrong bushing in the end. When hot it expanded and siezed the armature shaft.

[foureyedbuzzard]

Originally Posted by Terry S

With the PCM box lid off I can hear the relay's clicking when the key is turned to the on position. The starter doesn't make a sound.

I'll try testing the voltage readings when the key is turned to the start position.

This problem is really driving me nuts and I have a dealership saying that if its the PCM thats bad (I really doubt this), then it'll cost around 1400 bucks. Merry Christmas.

I'll look for the grounding spot on the engine. Not sure off hand where it is, but I'll figure it out. Thanks for your help, and any additional comments greatly appreciated!

Terry S

Don't ya just love dealers changing parts without troubleshooting ;-)
I agree, I highly doubt that there is anything wrong with the PCM. Also, the PCM and most other devices all have hard wired "grounds" and don't use the engine "ground strap" as a return current path. Almost all electronic components now have hard wired "grounds" due to terminal and mounting corrosion problems that play havoc with low voltage circuits.

Follow the negative battery lead(s) back from the battery to find the connection to the chassis and engine. I may be wrong with the ground connection guess(troubleshooting via e-mail just doesn't lend itself to much more than educated guesswork), you could have a bad starter/solenoid, starter relay, bad battery and or terminal, etc -- but I'd most definitely bet against the PCM

[Terry S]

Originally Posted by foureyedbuzzard

Gut reaction - you have a poor connection somewhere from the engine to the battery NEG terminal. Look at the connection lug for the engine "ground strap" on the engine itself. If it is not absolutely clean AND tight, when the motor gets hot the bolt expands very slightly lengthwise causing the loss of a good mechanical connection. The connection will "work" again after the motor cools and the bolt shrinks.

The continuity test means little due to the high current draw of the starter motor. You can't rely on a VOM resistance reading to prove the integrity of the connections. The VOM puts out < 3 volts and the current is a few milliamps - not enough to mimic the instantaneous heating of the connection present during starting.
While trying to start the car, take voltage readings starting at the starter motor itself. If possible, use a long test lead for the NEG connection and hook it directly to the battery post terminal. This eliminates any connection problems in the engine to ground connection while troubleshooting. If you have full voltage at the starter, check the voltage from starter to the engine itself. If lower, look for a bad connection in the motor to "ground strap" cable. Otherwise keep working back from the starter towards the battery until you find the problem. Don't overlook battery terminals and connecors, etc. Hope this helps

Well I checked the negative connection to the ground on the block (it goes to the top starter mounting bolt) That bolt is very secure and the connection appears to be good and clean. There is a washer between the neg cable end thingy and the block though. But its always been there. The pos and neg cables comming from the starter to the battery have no apparent cuts or frays, and the ends on both sides look clean and undamaged.

For the record, the car was running fine for 2 months after a new starter and battery were put in. out of nowhere it decided to stop working in a home depot parking lot. The starter was replaced again, but that didn't change anything. Maybe the battery or cables needs to be changed dispite appearing in good condition.

Again, all comments are welcomed!

Terry

[public]

seeing your last post I see that my "recall" story woun't be of any help.

[foureyedbuzzard]

Originally Posted by Terry S

Again, all comments are welcomed!

Terry

So much for all the arm-chair quarterbacking...

Have you checked the neutral start or clutch switch? I know it seems over-simplistic but somewhere in a rather simple electrical circuit: battery, ignition switch, neutral start(auto) or clutch switch(manual), starter relay, solenoid, starter; there is a problem (DUH!) Another item is the possibility of a theft deterrent system that could be in the circuit - generally they open the ground from the coil on the starter relay disabling the starter circuit. Sounds like you may need an electrical schematic for the car soon. Good luck, keep us informed, wish I could be of more help

[Terry S]

Originally Posted by foureyedbuzzard

So much for all the arm-chair quarterbacking...

Have you checked the neutral start or clutch switch? I know it seems over-simplistic but somewhere in a rather simple electrical circuit: battery, ignition switch, neutral start(auto) or clutch switch(manual), starter relay, solenoid, starter; there is a problem (DUH!) Another item is the possibility of a theft deterrent system that could be in the circuit - generally they open the ground from the coil on the starter relay disabling the starter circuit. Sounds like you may need an electrical schematic for the car soon. Good luck, keep us informed, wish I could be of more help

Thanks to both of you. You've been of much help. I've got the wiring schematic thanks to the service manual, and thats what I was figuring it was too.

The car is an automatic and the park/neutral thingy might be the problem. I didn't feel like ripping the whole console out last night The car is equipped with a KARR car alarm and shock sensor. I used to work for them so I've tried disabling it and I cant honestly tell if thats the problem (I wouldn't doubt it though).

The car is officially at the dealership (not the 1400 quote one) as of an hour ago however so I'll keep everyone posted on what they say. I'm hoping they think they can fix it with some replaced battery cables or ignition switch.

Thanks again!
(hoping for a $100 quote) Terry S

[public]

That "Park/Neutral Thingy" is not in the console. It is on top of the tranny where the shift cable attaches. Easy to change.

[Terry S]

Sorry, I ment that center console where the automatic shifter is.

But anyways, we got the car back and its fully operational. The car starts up cold or hot without any problems.

The problem was with the car alarm (I knew it!). It had some kind of short internally which was causing the engine kill to come on. The dealership removed the alarm and offending wiring harness. Total cost of $150 bucks for labor.

So thanks to everyone for your help, this one has been resolved.

Terry S

[public]

Cool, even if we were WAY off on our solutions.

[Terry S]

Originally Posted by public

Cool, even if we were WAY off on our solutions.

Hey public, this is a bit off topic, but thats an awesome avatar. Do you have that in a larger size?