Reply To: 2004 Automatic Rear Door latch

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#6715

bgrubb7
Participant

I finally got some time to work on this…

Not for sure what you mean my unplugging the motor and then testing power to the latches. It appears that all power goes through the harness to the motor (and Control Unit). With the motor unplugged, I couldn’t find any power to the rear latch. Anyways… moot point…

I did take a closer look at the rear latch/clincher assembly as you suggested and I now believe that was the culprit. The first thing I noticed is that when left the hatch open… (With automatic system switched to OFF) I could manually close the latching mechanism with a screwdriver and it would clinch shut and open with the rear door handle every time. Then I crawled into the rear of the van so I could open and actually pull close the rear hatch from the inside. With the rear panel off, you can easily press on the actual limit switch on backside of the rear handle to open.

What I found was that when I physically closed the rear hatch (as opposed to closing the latching mechanism with a screwdriver), that the failure is back. The door would open sometimes, then eventually fail to open from the rear handle command. Also the clinching action would periodically fail and this would always be followed by a failure to release when the rear handle was activated. I did notice that the rear latch didn’t seem to align perfectly with the striker, so with a little adjustment and careful dead blow hammering of the striker, I got them lined up perfectly. This helped, but did not eliminate the failure.

Second thing I noticed, was that during a failed attempt to open, when I activated the rear handle switch, I could hear a click from the control unit on the motor assembly. This suggested to me that the relay in the motor assembly was doing it’s job, sending power to the rear latch, but the latch wasn’t obeying the command. The open command would continue to fail (you get the warning or error beeps) and would not work again until manually opened with the manual lever and hatch re-closed.

Third, I noticed that after a failure to release, there would be no sound or movement from the motor on the latch assembly. I could tap on the latch motor with a screwdriver (much like you would on a sticky starter solenoid) and it would work on the next open command. So I’m thinking the motor itself is sticking or there is a bad connection in the motor with a brush or something like that.

I took the latch assembly off, and removed the latch motor. There was quite a bit of carbon dust buildup from the brushes. I cleaned it out with some WD-40 and a toothbrush, cleaned the carbon buildup on commutator and re-lubed the spindle ends with some white grease. Reassembled and reinstalled the latch assembly.

So far (fingers crossed/knock on wood) it seems to have done the trick. I opened and closed (Auto mode = OFF) dozens of times with no fail, and since then have been opening and closing in auto mode with no fails at all for that last couple days.

I’ll update if the situation changes… Thanks!!

  • This reply was modified 3 years, 2 months ago by  bgrubb7.