lex400sc

I just removed the gauge cluster from my car to take it in for some service work. It'll be out of commission for about two days. Here's my question, without the instrument cluster, will the car battery still charge? I know on certain GM autos, the battery doesn't charge without the instrument cluster connected. I'd hate to find a dead car in the morning, or worse, a dead car while heading out of the school parking lot. I don't know if anyone here would know the answer to that other than a hardcore Lexus tech.


Also, while driving back from the shop without an instrument cluster, I noticed a few phenominons. Firstly, my steering wheel was much lighter and much more sensitive to turning. I like it a lot. Another thing, braking was more effective when the AC was running. Before, when I tried braking with the AC running, there was more resistance in the brake pedal. Now it feels the same as if the AC and fan were disengaged. AC pulley still bumps the RPMs up though. Lastly, gear shifts were much more transparent. I could barely feel the tranny shifting when punching it onto the freeway. The acceleration felt the same as before though. My theory is that there is an ECU in that instrument cluster that controls much of that stuff. Without it, the car is functioning true to form and all around more responsive. I had about 50 miles of driving time without the instrument cluster, so I paid close attention to these things all the way back home.

Black94RX-7TT

I don't know this to be true for Lexuses, but it does hold true for 2nd gen RX-7s. In the RX-7s there's a vehicle speed sending unit in the cluster. It converts the rotation from the speedo cable to electronic pulses for the PS computer, and cruise. This could explain your PS behavior, as SCs do have variable assist, and without the speed signal, it defaults to full assist. Although I can say that my '98 still displays the vehicle speed correctly, and everything works OK (with the exception of the check engine light) with the speed sending unit disconnected at the transmission.

As for the battery charging, I have no clue (I'd suspect not, though, that's a pretty weird thing, unless of course you've got an ammeter in the cluster, in which case most all the current (excepting the starter) has to go through it first)....I suppose you could start turning on accessories and see if the headlights dim...or hook up a voltmeter to the battery and see if the voltage drops significantly as you put more load on it.

Intellexual

lex400sc--

Some of your wording confuses me:

"Firstly, my steering wheel was much lighter and much more sensitive to turning."

Does this mean the wheel was even easier to turn than usual? The Lexus steering is already far overboosted so if you meant that the steering became slightly tighter and BMW-like, I'd love to try this too.

If it was tighter and harder to turn, that would make it more sensitive to turning, no?


It'd be nice if there was something we could just disconnect behind the gauges that would stiffen up steering a little!

lex400sc

Black94RX-7TT, I hope to God you're right about the battery! The last thing I need is a dead one. If the power steering pump is controlled by the instrument cluster then so is the braking system because the vacuum booster is connected to the PSP and would thus apply more pressure to the master cylinder while applying more power to the steering. Cool.


Intellexual, the wheel is much easier to turn. Without effort even. This is making the steering much "tighter" as in I don't have to turn the wheel as much to get the vehicle turning in the right direction. I'm almost tempted to fly across a street corner and swing my steering arm across sending the car into a sharp tail drift!

Ryan

Hey Lex400SC,

When you connect the instrument panel afterward, you will have an airbag warning light that will not clear. This happens when the ignition is turned on without the instrument cluster. I would suggest doing a search on this. You've got to stick in two wires into this plug thing below the steering wheel and touch them together in a strange sequence. If you have no idea what I'm talking about - you will soon!

Good luck,
Ryan

lex400sc

Damn, that sucks ***!!! Is this just another annoying light on the dash or are the airbags actually non-functional until you fix it? Is the fix easy?

Ryan

I just did a search for you.


Here is a copy post of what posted on Ladman long ago. I am so happy people used it - I thought it died with the site! This is the post you should have read BEFORE you did anything =(
https://www.clublexus.com/forums/sho...t=airbag+light


Here's how to fix the code:
https://www.clublexus.com/forums/sho...t=airbag+light

lex400sc

Thanks Ryan, I'll start reading up!

lex400sc

Okay to clarify what I just read...

DLC2 is the auxiliary fuse box located under the dash above the left knee. In DLC2, there are two terminals labelled Tc and AB. I need two paperclips with wires attached to each of them. I use these wires to tap the car frame in the sequence of Tc, AB, Tc, AB and hold the wires each time for between 0.5-1.0 seconds. Then my last tap is to hold Tc down until the air bag light blinks. If it doesn't blink, then I try it again. Is this correct?

Thanks Ryan for bringing this airbag light to my attention!
Thanks VQT, you are the electrical encyclopedia!

Ryan

I don't remember the sequence of what to touch when, etc. So I am assuming the directions are correct. You will find the cap to this below the hood release. When you open the cap you will see the label on the inside.

Okay, here is the killer tip - you owe me - jk:

You will likely fail several times before you succeed. Expect to invest 10-20 minutes doing this. Also don't f-up by sticking the wires in the wrong holes and doing stuff - nothing to freak out about, you just don't want to cause more errors.

Here is the key - get some wire at Radio Shack that will slip in the hole (buy a pair of wire strippers if you don't have some already). Then, put these long wires in the holes and use the outside of the cigarette lighter for ground (don't touch the center part). Now, as you fail miserable the first 2 or 3 times, you can do so from the comfort of your leather seat rather than all twisted up under the dash. Okay buddy, if it works I want a beer!

lex400sc

Well tomorrow is probably going to be truth day. I'm expecting to get my instrument cluster back sometime then. Now I'm anxious!!! It's kind of fun driving without the instrument cluster cause now I can speed all I want and tell the officer "but officer, I don't have a speedometer to read! sob sob sob". I'm getting used to the lightened steering wheel and power assisted braking too! Oh well, it's good to know how much gas I have in the tank, when my engine is warmed up, and what time it is. Ryan, if this solves the problem, you can have all the beers you want! Wait! I didn't say that! You can't prove anything!!! Thanks for the tip though. What did you ground it to on the car? Do I have to reach a wire all the way into the engine bay to find a clean grounding point?

Ryan

Dude - the cig lighter outside part: neg = ground. Look up in my prior post.

Manaray

Lex, are you getting your needles worked on? I need a new speedo needle...

lex400sc

I'm getting the odo rolled back because my instrument cluster came out of a high miles SC. It's about 47,500 miles off. Makes it hard for me to keep track of scheduled maintenance. The guy is also going to calibrate the speedo too. I'll probably change out all the bulbs inside it when I get it back. Just to save the hassle of doing it later.

Ryan, sorry, I didn't notice that in your first post. I must have been out of it last night.

lex400sc

Just got my instrument cluster back... I installed it and no airbag warning light came up, WOOHOO! At first the speedometer wasn't working so I unplugged everything and examined the wiring harnesses. Apparently pin number 13 on harness number 24 was loose, probably from me jerking the plug out by the wires. I soldered it back in and vwa-la! Everything is working perfectly. I miss the fully-assisted power steering though .