KahnBB6

iTrader: (5)

I've searched a lot on this topic and have come up with almost nothing.

My car is a '93 SC300 factory 5-speed. The fuel gauge in the cluster hasn't read as completely full or accurately displayed the fuel level since I bought the car. I always knew I'd have to deal with it and I did just yesterday by replacing the fuel tank sending unit with a new factory part.

This didn't fix the fuel gauge inaccuracy so I guess (??) I have a faulty or out of spec fuel gauge in my instrument cluster.

Basically, other than buying a new OEM 5-speed gauge cluster from Carson Toyota, how can I fix this? I have no other issues with needles or lack of illumination. Everything works fine except the fuel gauge is always off and doesn't let me know how much gas I have once I hit 1/2 tank (my gauge reads 1/4 full at that time but goes no lower).

I know that lextech lighting repairs needles and backlighting but I don't think they recalibrate anything or repair electronics... do they?

I'm just tired of not being able to take the car on a long trip because of my fuel gauge and want to get it fixed.

Any suggestions, guys?

Edit: I discovered that the fuel gauge is actually a part separate from the rest of the instrument cluster. Still, I'd rather not buy a new gauge if this one is just in need of calibration.

KahnBB6

iTrader: (5)

I have found one ebay listing for a fuel gauge repair guy:

http://cgi.ebay.com/ebaymotors/ws/eB...ht_1730wt_1167

It's for 92-94 LS400's. I have asked him if he also repairs SC fuel gauges. Is anyone familiar with this person's repair services?

KahnBB6

iTrader: (5)

No one?

I spoke to Collin in the Carson Toyota parts dept and he recommended a Lexus Master Tech to speak to me about it. When I described the problem and that the new sending unit had no effect, he said it's a bad cluster issue rather than just the fuel gauge itself. Great.

He recommended a repair facility based in Massachusetts to get it fixed.

I'm trying to figure out why it would be the whole instrument cluster rather than just the fuel gauge which is listed as a separate part.

Can anyone confirm this?

joliroger4

Take the sender out and manually operate the arm out of the tank and see how the gauge reacts. I had an issue and it turned out the sender was hanging up on something in the tank. I just had to tweak the sender arm a touch and it was fine after that. Before I repaired this, it would hit 1/4 tank and never go lower.

KahnBB6

iTrader: (5)

Thank you. I don't think it's the sender, however. I would try that but since my old sender and the new one I just put in are having exactly the same effect on the gauge I am thinking it is something in the gauge cluster.

I've read that LS400's have bad capacitors in their instrument clusters that cause almost the same issue :/ What doesn't make sense is that nothing else on the cluster is malfunctioning.

joliroger4

I completely understand what you are saying. I also took out my gauge cluster twice and the sender 3 times before I got to the bottom of what was going on. I even took the sender out, dismantled it and cleaned it. I did find out though that knowing something in theory and knowing something for a fact can sometimes be very different things. Besides, operating the sender by hand outside the tank is free to try. You don't know, someone could of done the fuel pump in the car before you bought it and maybe something in the tank did not go back in the way it came out which would be why both senders have the problem. I am not trying to tell you what is wrong with your car, or what to do with it, just would hate to see you throw time and monye at it. I know that can suck.

KahnBB6

iTrader: (5)

For anyone who is interested, Lee Thomas of the Roadcarreview channel on youtube responded to my fuel gauge fix question on a video tutorial showing you how to change the SC dash cluster bulbs. He put up a set-by-step guide showing how to replace the SC300/400 fuel gauge and adjacent water temp gauge with a new or rebuilt part. It shows that you don't have to send your cluster in for this repair. Get the replacement gauge and follow the instructions. And here I was thinking I needed to find circuit board soldering instructions...

http://www.youtube.com/watch?v=zESeIRwHcf0

Very thorough and straightforward. When I get back after the holidays this will be the top project on my list. Lee, if you're reading this, thank you!

(Just to note, when I called my Lexus parts guy and asked for a 1993 fuel gauge he stated there were two versions depending on the month of manufacture for MY1993 cars. I don't know any more about it but giving him the VIN number of my car made it an easy match. Since my car is a 5-speed manual trim there may have been some odd variation in the gauges between it and the auto SC3 or SC4 models. I have no idea but it might be good to check when ordering/searching for your car)

KahnBB6

iTrader: (5)

I just thought I'd add some addendum information in case it hasn't been posted elsewhere. In case someone is performing this fix and needs the backlight bulbs too the CORRECT bulbs are:

P/N 83109-24040. Listed as "Green" or "Bulb Holder"

The bulb had a GREEN rubber condom on it like the original, but it was of a smaller size. I'm thinking there was either an issue with my bulb or there is an issue with the information Lexus/Toyota provided. I drove 150 miles round trip just to pick the part up and to make sure it was the correct bulb. Best bet...Order one of each.

For reference, there are three bulbs listed for the SC dash:

Green 83109-24040, Blue 83119-24570, Unknown 90099-53007

O. L. T.

iTrader: (17)

Those part numbers have been in this forum for ten years as well as a complete writeup on the entire cluster and every single piece of it detailed in each section with pics and diagrams in the ice blue thread, BUT it is a complete waste of money to buy the factory bulbs which are overpriced and hard to get when you can go to any auto parts store and buy #24 bulbs which are a BETTER match for the car then even the OEM bulbs because they were chosen for their ability to withstand the harsh voltage swings in OLDER SC's when things aren't perfect, like a brand new car on paper or a showroom floor is. So while the OEM bulbs are dying off in a year or two from voltage spikes the #24 at any auto store rides 2.8 volts above the alternator's max potential to absorb spikes and last as long as you will ever own the car. That was posted in March of 2003 and repeated in nearly every thread about backlight since over the last near decade. I know you've only been here a year, but look around and save yourself a lot of trouble and time with the info that is out there. Less than 2% of all SC's out there have a "clean" electrical system that does what the original SC was designed to do when it was built 15-20 years ago. MOST have bad spikes, dips, surges, none of the grounds are 100% and all the electrical has a ton of mileage on it. Things have changed, and they are better when they are evaluated for todays situation.

KahnBB6

iTrader: (5)

O.L.T., I defer to you on this. Your knowledge of electrical systems is always welcome and to be learned from. I was looking for the part numbers but couldn't locate the thread name. I did my bulbs a few months ago and this was just pulling from my notes that I thought I had lost. A guy came by earlier today to pick up an airbag and was asking about cluster bulbs so I tried to help.

If my newish factory green bulbs go out I'll be buying the #24's as you suggest. And I'll steer him to your post.

Currently I am looking for bulbs brighter than my factory ones for the climate control panel. I had my LCD and backlight bulbs replaced by a reconditioning service and it works fine but the climate backlight is. It as bright as my stereo backlight. That issue I'd love to fix.

O. L. T.

iTrader: (17)

Factory bulbs peak at EXACTLY 13.7 volts, past that the filament heats up. That's why the #24 (which can handle 15v to the filament at safe temps) are best suited.

I have seen the bulbs used by the "re-conditioners" that stick the 10v bulbs in and call it a day and those are just as susceptible to spikes which is why I designed the circuits to ride above the 13.8V threshhold when I mod them so spikes are never an issue and they are as bright as possible. My climate (which is currently awaiting a new LCD to come in that I ordered) is a good 35% bit brighter than my radio and it is modded.

Unfortunately after 14 tries I can't get a picture that shows a huge difference since it just blows the contrast out.

KahnBB6

iTrader: (5)

^^ Your camera is averaging out the exposure but I can tell a bit. Aren't those backlight bulbs on the climate controller solder-in and not screw-in, however? If not then are the #24 bulbs you specify are the same or the instrument panel and climate?