'01 LS, Need Driver Door Module (DDM) info...

[chollybennett]

Can somebody tell me more about the DDM, as it relates to remote lock/unlock info? Here' the problem, and what I have deduced so far: I have intermittent operation of my remote lock,unlock,trunk features. This happens with either of my two key fob units (both of which are new and have new batteries).

There's a pattern: In the cool of the evening or early morning, all usually works as it should. As the day heats up, any operation from a distance does not happen, but usually works from within a foot or so of the DDM. When it gets hot in the sun, then features do not work at all, but return after sunset and cooldown.

My theory on the hot vs. cool thing is that there is a solder break on the circuit board in the DDM, like maybe a cracked joint around a component or edge-connector lead or a cracked trace on the board itself, and that the heat buildup forces some warpage and an open circuit.

The fallacy that I see to this thinking is that it should be either a "work" or "no work" situation, but there is that gray area when the system will work only from close range. So one question would be: What about an antenna situation? What functions as the antenna for the remote lock system? Is it internal to the DDM, or something like a connection to the radio antenna or rear window defroster?

I have looked into replacing the DDM, but it requires a data dump from the old part and subsequent reprogramming of the new one by a dealer, who wants a ridiculous sum for this relatively minor service and for the module itself, which they also want to sell you (of course). Replacement modules can be had on the net for like $30.

Can I get some advice from somebody who knows this system better than I do? I can deal with the circuit board issues to component level, if necessary, but it's the antenna setup that will determine how I go about it. Thanks in advance for any help...

[shorod]

I'd have to take a look at the service manual wiring diagram to determine the way the antenna works. The family and I are camping this weekend so I won't have a chance to look at the diagram this weekend. If there is an antenna though, there's a good chance the solder joint for the antenna could be the issue which would also explain why it will work at close range more reliably than long range. You might also want to consider a filter capacitor that has gone high in ESR or has a faulty solder joint. The ESR will tend to increase as the capacitor heats up. If a filter cap is essentially open circuit the RF section may not be able to pick out the signal as well when the signal to noise level decreases at range.

-Rod

[joegr]

Yeah, I would bet on a bad capacitor or other component in the RF receiver circuit inside the DDM.

[chollybennett]

Sounds reasonable to me... Is the memory in the DDM non-volatile? I'll obviously have to remove it to snoop around inside. If not, is a memory dump doable on any other equipment besides the dealer's computer?

[joegr]

The memory is non-volatile.
The new version of the AutoEnginunity tool may be able to do the programming.
The only thing that really needs to be programmed is the serial numbers for your remotes. You can just reset your seat/steering wheel/mirror memory positions yourself.