cjs18

I guess it was bound to happen sometime… My '02 top doesn't operate. Here's the story in the hopes that some of you guys may have some ideas: It is currently in the up and locked position and the open / close switch on the panel now does nothing - no red light, no chime. In addition, the driver and passenger windows no longer have the auto-up/down function although both operate perfectly otherwise. In addition it is not possible to operate the windows for 30-40 seconds after turning the ignition off. Outside the car, holding the key unlock button down after unlocking for a few seconds there is a long beep but the windows do not lower. The doors unlock normally. The button on the left side of the glove box is set to enable the remote trunk release. The trunk releases normally with the panel button and remotely using the key. Nothing traumatic has "happened" to the car. It just woke up this way. We have had some beastly hot weather though.

So I've checked the all the fuses on the vehicle for continuity - all good. I have disconnected the battery for an hour to see if absence of power might reset some misbehaving ECU. No results. Everything else on the car appears to work fine besides what's mentioned above. The only relay that appears to be directly related to the PRHT is IG which seems to be working.

It's probably about time to get some scan codes read, so I am wondering if anyone has enough experience with the typical consumer-type units that are available to know if they show the manufacturer-specific codes in addition to the usual power train stuff (POxxxx). There are about 50 specific codes in the B25xx range that pertain to the sliding roof system and it would be useless for me to get a scanner that couldn't display them. Anybody have one or tried this? I am aware that I could probably go to one of the other parts stores to see if they can read Lexus codes and I may do that. If the combined symptoms described sound familiar I'd sure like any info you might have on the solution. I have the S/M and EWD documentation for the car. Thanks for any help.

VVTiBob

Sorry to hear about the issue with the roof...rather than wasting time and effort at various auto pars stores I'd have Lexus do the diagnosis, give you the error code. From your description sound like one of two possibilities. A switch is no longer setting the correct state. Or the roof ECU has gone the ECU heaven. My bet is a switch. Since you have the FSM you have all the info on the error code.
With the rash of roof issues lately, some with unique solutions, it would behoove you to do a thorough inspection of all moving parts for any foreign debris. And, while you're at it, a clean shot of compress air to dislodge any dirt or oxidation build-up wouln't hurt. It worked in two recent cases saving the owners thousands from the dealer quote.

cjs18

Bob, thank you for the response. I agree that the shortest distance between two points in this case is the dealership and I appreciate the nudge in that direction. I may pop out the luggage compartment garnish and check out some of the switches that I can see and touch. If nothing obvious I'll set up an appointment for next week. I have my fingers crossed that you're right. From the symptoms crossing over into window operation I thought this might have ECU written all over it. Will see. Thanks again.

JohnnyCake

No lights could just be that the ECU has been given inconsistent information.

When Habious and I were working on my top problem, the "no light at the switch" condition was generated when there was an inconsistent condition reported to the ECU. In our situation, it was when the last switch state told the ECU that the trunk was open, but we jumpered it so it would show that the trunk was closed.

This is also similar to the rear-window mod. The last state the ECU knows is windows down. Then, using the mod, you manually open the window. When the top switch is then pressed, the ECU has conflicting information and the top light does not illuminate.

My guess (and its only a guess) that an inconsistent condition is being reported by your rear windows.

You are definitely not going to get the correct code from a non-Lexus test unit. And Lexus is not going mess around trying to actually repair what you have -- they will just start replacing components based on the shop manual flow chart.

When I had the top problem, I went to Lexus and paid an hour fee just to get the DTC code, which pointed me to the specific issue. With help from those in this forum (especially Habious and VVTiBob), we diagnosed and repaired the problem -- I am sure I saved thousands of dollars.

Good luck!

cjs18

I agree. I've studied the FSM diagnostics and EWDs enough to understand that many of the DTCs reported can cover a number of faults. Some appear to be catch-alls that could result in multiple component swaps and that scares me to no end. But I think it's a starting point though to have the codes and an assessment from the dealer's technicians. I'm prepared to do some further investigative work if they aren't confident enough in their findings to commit to a specific scope and cost to make it right.

cjs18

As a quick update, I brought the car to the local Lexus dealer today. They spent about 3 hours with it and obtained one DTC: B1273 - which indicates that either the sliding roof ECU isn't communicating or that there's a wiring harness problem. The technician verified power and ground to the ECU and stated that he was 90% confident that the ECU was the problem and recommended replacing it before any further diagnostics. They didn't have a vehicle from which to substitute a known good ECU (p/n 89720-24010) or they would have done that to make absolutely certain of the diagnostics. All in all they spent over 3 hours on the car and charged me $150, which seems completely reasonable especially since I really had no other way to get that code. The technician offered that if I were using a secondary market ECU I should find one from an SC manufactured between 05/01 and 07/02, which is interesting because mine was built in 02/01 (!). The ECU itself does have a metallic foil plate with some numbers printed on it that might be a mod status or revision code but if you look at Sewell's parts listings there seems to be only one p/n from 2002-2005 vehicles. Anyone able to offer any comments on interchangeability of this part?

JohnnyCake

eBay has that ECU for $200 OBO at this link.

I can't image what they did for three hours. According to the shop manual that DTC code does point to either the wiring harness or the ECU. I can't image the cost/hassle of replacing the wiring harness. The ECU should be plug and play. Let's hope for a simple fix.

Keep us posted!

cjs18

I located a roof ECU on eBay for $142 shipped, with a 14-day return policy (!). It will be a couple weeks before I have a chance to do the substitution but I will update regarding plug-n-play. Simple would be good.

cjs18

Update: I received the replacement roof ECU yesterday, considerably earlier than expected. So I was able to remove the old one and test the replacement now instead of waiting. All is well - all the symptoms described in my first post are gone and the top and windows work fine. The donor vehicle was a 2002 and the part number was an exact match. The only surprise was how little of the luggage compartment garnish needed to be removed to access the electronics. I guess I was picturing something worse from the steps outlined in the FSM. Total cost including time for the charge for the dealer to diagnose and isolate was under $300.

VVTiBob

Good job, nicely done. Thanks for the update.

def300s

Great information. Definitely one to bookmark for future reference.

JohnnyCake

You definitely just saved yourself over a grand! Having been there, I know what a relief it is to dodge an expensive bullet and get the top working again. Congrats!

joecal

got the parts and special toolsI will be doing it tomorrow.

After seeing all the recent posts Looks like this is a great resource now that the SC is 7 years old now

JPBJR

Thanks so much for the update. I am bookmarking for future reference!

Idaho430

Wish mine would have just been the ECU. Our '02 gave a different code at the dealer than what you had and it turned out to be a 'dead spot' on the drivers side electric motor for the roof. $852 quoted for a new motor at the dealer. Found one at Atlantic Auto Salvage (via eBay) from an '06 with 22K miles for $299 shipped. Dealer installed (this was no plug and play) and the roof works perfectly again. I had to pay for installation in this case but saved over $500 by buying a used part.