Rear wiper only works with back door open? ECU or ground wire issue?

[viperdriver69]

I've found 2 threads with same issue but neither had a resolution, appreciate any help! 1998 HDJ101K right hand drive (JDM)

Rear wiper works like a charm if either rear door or rear hatch is open, so wondering if it's a problem at the common ground between those door courtesy switches and the rear wiper - they all seem to go to the same common ground in the cargo area.

I'm not sure how to test / validate that, or isolate the problem vs. the instrument ECU. Not exactly a pro at reading the diagrams.

Any tips? Included the wire diagrams below. Thanks!

 

[asmara]

I can't answer your question but seeing zero replies, I can add a couple of things.

First where did you get the wiring diagrams? They may be accurate, I don't know, but the RHD HDJ100 uses EWD342F. That one shows different grounding points for each.

That being said, I'd replace the Instrument ECU. I just ran through a similar situation chasing down a door-ajar light that was always on. Spent hours checking grounds and grounding points. It was the instrument ECU. For the money to pick up a used one, it would have been worth saving all that time troubleshooting. I made this post about my experiences. Depending on your options, you may be able to use other ECU models. You don't mention what your Instrument ICU is (and I haven't been able to find a correlation between higher part numbers and year), but you should be able to find a compatible one from an LC or Lexus online.

 

[viperdriver69]

I can't answer your question but seeing zero replies, I can add a couple of things.

First where did you get the wiring diagrams? They may be accurate, I don't know, but the RHD HDJ100 uses EWD342F. That one shows different grounding points for each.

That being said, I'd replace the Instrument ECU. I just ran through a similar situation chasing down a door-ajar light that was always on. Spent hours checking grounds and grounding points. It was the instrument ECU. For the money to pick up a used one, it would have been worth saving all that time troubleshooting. I made this post about my experiences. Depending on your options, you may be able to use other ECU models. You don't mention what your Instrument ICU is (and I haven't been able to find a correlation between higher part numbers and year), but you should be able to find a compatible one from an LC or Lexus online.

Thanks for that - not sure, I've been using EWD339U, but now that you point it out that does look like it's for the 2UZ. I'll go back and see what's different, but if the grounds aren't the same like you said it's back to square one. I'll see what ECUs cost and may just take your advice.