Chrysler Repair: Evaporative emission system problem (P1494/1495 codes), xerox copy, solonoid

Question
I have a 97 T&C van. 9 Months ago the engine light came on and the codes indicated the leak detection pump. The condition was that, after the codes were reset, it would be a few miles before the light came on again. I replaced the LDP and all has been well until a month ago. It had been raining but it had been in wet conditions prior to this. The Engine light came on. The codes once again indicated 1494 and 1495 (LDP). However this time the light comes on the instant it is reset - no delay. I began debugging the problem and found that there was no voltage on pin 2 of the LDP - the voltage pin. This is connected, on the power block, to a DTC. To determine if a lack of power was the problem, I jumpered the battery to this pin on the LDP connector. No change, the light comes on and the code is set instantly after being reset. I have also tested the LDP and determined that the solonoid does, indeed, sound like it is working when energized. I'm assuming that it may be possible that the LDP failed and somehow took out the LDP. Does this sound reasonable or is there some other explanation? Thanks for your help.

Answer
Hi Al,
I think the easiest way to help with this one is to send you 4 pages from a powertrain diagnostic procedure manual that I have for the LHS cars in which a set of tests is laid out for each of those codes. I personally haven't had to work on such a system as my newest vehicle is an '89 but I think these pages would give you the answer. I can xerox copy and postal mail them to you on Monday if you respond with a mailing address. Use the 'rate the expert' tab where there is a space for comments.
The possible causes are:
LDP vacuum supply  ('94 only)
wiring harnesss intermittant (both)
LD pump (both)
LDP switch sense circuit shorted to ground (4 only)
LDP switch sense circuit open (4 only)
fused ignition switch output ('95 only)
LDP solenoid circuit shorted to ground (5 only)
LDP solenoid ciicuit open (5 only)
Powertrain control module (both)
There are about a half dozen tests under each code to sort this out. Let me know if you need the wiring diagram for the circuit.
Roland