Hello! New user here asking for some advice.

Got a 2001 Grand Caravan about six months ago with only 85k. Only issue I've had was an ever-returning CEL P1684 code that will not clear no matter how long I've driven or reset even with new battery. (reset via battery, but its been well over 50 starts - I've given up on it)

Had a fluid exchange done on the transmission when I got it, made sure they used ATF+4 but had them add Lucas transmission fix for some stupid reason. (thought as a preventative) This was about six months ago. I have a jug of new ATF+4 and plan on using return line to flush out the Lucas mixture for fresh. Waiting to resolve this issue first.

Last week I've noticed a transmission fluid leak under the van... not large but concerning enough. After some research I decided to replace the solenoid pack seeming as a safe bet. Got a Borg Werner and it installed fairly easily making sure to keep everything clean. Also replaced the input sensor and added a transmission cooler just for giggles. (plan on doing a long drive this summer)

No issues with shifting or drive-ability and no apparent fluid leaks as of yet. Although the CEL came back on after driving as usual... except this time it included a P0700 code with P1684.

Re-installed the original speed sensor (read somewhere that generic ones can be bad out of box, didn't seem to have any issues tho.) Reset via battery and it has returned.

Checked ground strap to motor, reads ok but looks corroded, added a wire from solenoid bolt to frame ground just to be safe.

My question before having to take this in for TCM to be read... will the codes in the TCM continue to pop the CEL even after clearing the computer codes? (Regardless if I fixed the issue that is) Obviously we cannot reset the TCM codes... I do not want the stealership finding 'old' codes and attempting to fix something I may have already!?!

Should I just have them clear the TCM codes and do a quick-learn?

Did I get a bunk solenoid pack? I can ohm solenoids out... need to do that I guess. Need to look for a pinout... I'll try to have that done before next update. Probably should have just replaced the seal given my old pack didn't have any apparent shifting issues.


Thanks in advance!

 

Did you check the fluid level both cold and hot? You might want to check the temp of both cooler lines with an IR gun, after the van has run for half an hour or so.

 

I may have overcompensated for the transmission leak/solenoid repair loss... used the return line to drain the extra fluid.

Found my transmission cooler isn't doing much of anything at the moment, needs re-plumbed into the return. Thought I had traced the hoses correctly... >_<

Upper rad = HOT IN (from right hose output on trans)
Lower rad = COLD RETURN (to left hose return on trans)

Thanks for the tip!

Appears P1684 is the TCM saying it's lost power/ground. Obviously the transmission still shifts so its got power... checked the fuse for B+ anyway. I've been having trouble with this code prior so there could be an issue with the alternator or voltage regulator? Hopefully not the TCM.

Even with a new battery when the van downshifts upon slowing down (to a stop sign for example) the HVAC blower and headlights will audibly and visibly dim. That could be when the TCM is losing its voltage and triggering the persistent code? Just an idea, maybe its normal...?

For those who may be suffering similar symptoms I'll share what the dealership says friday.

 

Before taking it anywhere you should at least do a load test of the battery with a multi-meter. First check that it has at least 12.5 volts with the engine off. Then with the engine running, it should read somewhere between 13.5-14.5 volts. If so, next have a helper turn everything on, one at a time and leave them on. As things get turned on, they should either not change the voltage at all, or (for some of the larger draws) cause the MM voltage reading to drop a small amount just momentarily, but then bounce right back quickly to the original running voltage. If the alternator is not performing as above, a parts store can confirm that it's going South. If so, an alternator replacement is not a difficult DIY job.

 

P0740 torque converter not locking up...

I'm under the impression this is a different solenoid WITHIN the body of the trans. Yet some forum posts suggest trying a solenoid pack replacement... how is it related to the TC?

Going to change trans filter, check for debris, flush fluid...

Alternator looks to be in our future as well.

 

Update -

Transmission started to whine and and began slipping while on the highway.. she finally gave up moving altogether. After it cools off it moves for a bit then slips and slips....

Thanks

 

You wrote in the previous post that you were going to drop the pan. Did you do that, and if so what did it look like in there? Also you should consider removing the cooler that you recently installed (and hope it's not too late).