Leak detection pump: '02 t & c

Last Edited By Krjb Donovan
Last Updated: Mar 11, 2014 07:48 PM GMT

Question

QUESTION: I followed the procedure for troubleshooting the LDP for a 2002 Chrysler TC. I have 12v on pin 3 with the key in the run position. With the key off I rung out and checked for a short to ground of pin 72 and 77 with both connectors off at the pump and the ecu. I even checked to see if 72 and 77 were shorted to all other pins on the ecu wire harness. All tested ok.

I connected 12 v to pin 3 and connected pin 2 to ground to fire the solenoid. You can hear it switch but it didnt sound strong. I than checked to see if I got 12v at the sensor pin 1. I did not.

With everything hooked up and the car running. I had 12v at pin 3 and can only get 12 v from the positive side of the battery to pin 72 and 77? I expecxted to see 12v to ground. If you disconnect the connector on the ltp you can hear it switch a little and some vacuum passes threw the solenoid to the diaphragm.

My question is, with a cold engine how long does the pump pump when the key is turned to the on position? Does it do it repeatedly? It just seems like when i turn the key to the run position it just stays on, There is no cycling of power to pin 2.

Does the ECU sink the 12v supplied to the solenoid?

ANSWER: Hi Ed, I found your question in the 'pool' to which Kevin referred it. Where do things stand now? Roland

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

QUESTION: I am about to send it to the dealer to have a new ecu installed. If that don't work the cost of having it repaired will deem the car trash. The car runs great otherwise. Hate to junk it.

ANSWER: Hi Ed, What is the fault code number that you are trying to correct? What does "DTP" mean which you listed as the Subject of your question? What is the manual you are using to troubleshoot the LDP? What is the size of the engine (L)? Are you working on this code because you can't pass state inspection? By 2002 TC do you mean Town and Country? Roland

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

QUESTION: I was frustrated. Not really sure why I typed that. Auto correct maybe. The fault code is 1495 which I cannot reset with my fault detector . Yes it is a 3.3 town and country. And yes I need to get threw inspection. I scanned the internet for some troubleshooting tips and obtained the correct wire harness pin configirations for my van. I am an electronics tech for a pharmaceutical co and do back yard restorations on my classic cars. I like to keep old things running . The college bills are another inspiration . It seems with the connector unplugged from the ldp when starting the van cold it should light a test light wired from pin 2 to 3. It does not. Had some other issues about one year ago electrically because the harness was cut along the block and the dealer replaced a piece of wire and wrapped some rubber hose around the harness. Some fix hu. Guess its better than replacing the harness . It would be nice to get a wiring diagram or the theory of operation of that circuit via the ecu. Help.

Answer

Hi Ed, The circuit is not complex. 12V is supplied out of the ignition switch on the pink/gray at pin 3 of the plug. Pin 1 has a violet/white wire to pin 72 and is called leak detection pump switch sense, while pin 2 has a violet/blue to pin 77 of pcm and is called the leak detection pump solenoid control and both those wires are straight shots with no splices. I don't know the detailed protocol for what the pcm is trying to do but the trouble shoot suggests the following possible causes for the 1495 code: wiring harness intermittent, the leak detection pump itself, the ignition switch output, the solenoid control circuit shorted to ground, the solenoid control circuit open. So check the wiring and absent any anomolies the pump itself may be faulty. Please 'rate' my answer (see below). Thanks, Roland

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