Mechanics

NO START WHEN HOT 03

2003 Dodge Caravan • 6 cylinder FWD Automatic • 108,000 miles

03 grand caravan 3.3 flexfuel, 108K car starts great when cold, after driven approx 20 miles or more and shut off, will not crank. When the key is turned on, there is a clicking noise underneath coming from the leak detection pump. When this chattering stops, then the car will crank and run. Just started 2 days ago. No check engine light on.
Avatar
Lnova
June 1, 2011.



After working over 35 years on many types of Chrysler products, I have never seen (or heard about) a "leak detection pump!" If the starter cranks the engine when cold, the battery is probably OK. But if the charging system (alternator and regulator) is failing, then the battery may be too discharged to start the vehicle again, after being continuously drained by many electrical loads, if running the engine without adequate charging current being delivered back to the battery. But any chattering you hear is probably the stater solenoid rapidly cycling due to (1) low battery charge, (2) bad or intermittent connections in the starter circuit or (3) bad or intermittent contacts in the stater relay. All that is assuming that there are no loose connections in the electrical system (such as battery terminals, ground wires, etc.).

Tiny
Gizmoguy
Jun 1, 2011.
I appreciate your response, but there is a leak detection pump. It is between the vaccuum canister and the purge valve under the van. It pressurizes the system for the PCM to check for leaks. Here is the oem part number 4891416AD. You will find it on the internet. I disconnect the electrical connecter from the LDP (leak detection pump) and the chattering stops. My only thought is that the car should still start with the bad LDP, but it doesn't. The electrical system is charging properly. If you leave the key on long enough, the chattering stops and the car will start. Is something else holding the circuit open? When the chattering stops, you here a relay close up by the fuse box. There are only 2 types of relays in the fuse box, so I rotated them all 1 position to rule out a bad relay. Thanks for any more info you can give me.

Tiny
Lnova
Jun 1, 2011.
If disconnecting the LDP pump connector stops the chattering sound, then there is probably a defect related to that circuit which is putting an excessively heavy electrical load on the battery. It could be a bad pump or it could be a defect in the wiring harness (such as damaged or pinched wires). Have you tried leaving the pump disconnected to see if the starting problem disappears? That is probably not a long term fix, but it could be a good method to isolate the fault.

Tiny
Gizmoguy
Jun 2, 2011.
Thanks for getting back to me. Disconnecting the LDP does not solve the starting problem. I actually took the pump out and put it in my sons van, (he has the same year and model) and he had no problems at all. I tested the crankshaft sensor and the camshaft sensor to see if they were shorting out, because they could send the wrong signal to the PCM and cause it not to crank, but they are good. I tested all my power points and grounds for the sensors and PCM, they were good. I even tried to jump the starter at the solonoid when this is happening, and the starter will crank but the engine will not start. When I disconnect the harnesses from the PCM the noise stops. It seems that everything is pointing to the PCM, and the problem is getting worse. I called around about the PCM and no one here in Houston has one. They said they are that prone to failure and they sell quickly. My son had to have his replaced at 60K, but it was still under warranty. I think I am going to order one on the internet, but I am leary about not knowing the reputation of some of the rebuilders. Does it sound like it could be the PCM to you. I appreciate all your effort.

Tiny
Lnova
Jun 3, 2011.
By any chance, is your vehicle equipped with any kind of anti-theft feature? I know a man who has a Chrysler New Yorker with an anti-theft feature, and that engine will not fire either, until the anti-theft system stops cycling the interior lights and exterior lights! Then the engine will fire right up. If you have an Autozone near you, they have a policy (at your request), of connectiong an OBD-2 scanner to your vehicle and reading out the fault codes, at no charge. There are no gurantees of success, but knowing the fault codes just might give us insight about what is going on with your van. Another question: Is your vehicle equipped with any kind of load-leveling system? (Air shocks with an electric pump that automatically compensates for unusual loads) Those are notorious for causing heavy electrical loads and causing starting problems due to a resulting weak battery! As a last resort, you might try disconnecting your battery completely for about 30 minutes or more, which accomplish a full computer system reset. If successful, the wipers should make one full sweep and then park, upon reconnecting the battery.

Tiny
Gizmoguy
Jun 3, 2011.
About the full computer reset, I left the battery disconnected overnight, and when I hooked it up in the morning, the wipers did not move at all. I did have it scanned by AutoZone a few days ago, there were no codes. No load leveling system.

Tiny
Lnova
Jun 3, 2011.
Failure to acknowledge a computer system reset with a wiper sweep is indicative of a PCM problem... Or the connections to the PCM module! It is a lot cheaper to make sure the problem is not connection related. One thing you could do is, with the battery disconnected, remove the connector(s) from the PCM module and inspect them for any trace of corrosion or moisture. If any is found, clean it up the best you can. Then lightly spray the connector(s) with some electrical contact cleaner (NOT battery terminal spray!) And then reseat the conector(s) a few times. Also, you should verify that there is no ground interruption problem to the chassis or the engine! One thing that I personally have experienced on Chrysler products is, bad connections developing at the (usually multicable) battery terminals themselves! One easy test for that is, with the engine first cold, then later, warm, Turn on the headlights on high beam, and, while watching the headlight brilliance, mechanically move the battery cables around aggressively, all the while, watching for any change in brilliance or flickering of the headlights. If any change in brilliance is noticed, either replace the terminal involved or replace the entire cable. Has the vehicle been in any accidents or floods? PCM modules would not likely be OK when cold and then bad when hot... But anything is possible! Also IF you replace the PCM module, you will probably have to have it "flashed" with the VIN (vehicle identification number) to make it fully operational. If you don't, the odometer will likely not work at all, but most of the gauges will still work (unless they are digital readout). Good luck!

Tiny
Gizmoguy
Jun 3, 2011.
If it turns out that you do need a replacement pcm (aka ecu aka ecm), Look for a warranty and "plug and play" (no flashing or update required) and free shipping for best value!

Tiny
Gizmoguy
Jun 4, 2011.
That last hyperlink I gave was kind of goofy. Sorry about that! Here is a much more targeted hyperlink that would work best with Google (since it involves site search). Don't miss any characters if you copy and paste the link into your browser!

Site: ebay. Com 03 (Caravan OR voyager) 3.3 (pcm OR ecm OR ecu) -"90" -"91" -"92" -"93" -"94" -"95" -"96" -"97" -"98" -"99" -"00" -"01" -"02"

Tiny
Gizmoguy
Jun 5, 2011.