My VSC and VSC Off lights came on a few months ago and never went off since. I purchased an ABS/VSC module off eBay from a 1998 GS300 which said it would work on the 1999 also. I unplugged the harnesses from the old module, plugged in the new module, turned the key on, the VSC and VSC Off lights did not light as they typically do; however, the car wouldn't start.

I unplugged the new module, plugged the old module back in, and the car still wouldn't start. I'm confused as to whether the module could have caused this, if I tripped a fuel shutoff switch/fuse, or if it was some loose wires somewhere?

The red immobilizer light goes out when the key is inserted so I'm guessing the ECU is fine. The check engine and oil light light up and stay lit with the key in the on position (Not sure if this is normal or not but it does that on my Acura also which is normal for that car). The one thing I did notice is that when I turn the key to the on position, I don't hear any noise coming from under the hood like I usually do. When the car worked in the past or before I unplugged the module, I can hear something running up there under the hood. It sounds sort of like when the fuel pump engages and is priming fuel. It's some sort of electronic pump noise in my opinion and it never stops ... at least in the past it never stopped, which I thought was weird, and it just kept making the noise until I eventually started the car. Now I don't hear anything happening up there. This makes me wonder if I blew a fuse, relay, or if there's some sort of fuel pump shutoff switch that got tripped.

Any advice on what to look for would be greatly appreciated. Also, would the ABS module I bought cause the car not to start? I didn't think so because when I bought the car the ABS module was laying on the floor and I was able to start the car without it even being connected although the brakes were hard as bricks. I've also heard some of these modules need to be re-programmed, would I need to do that on this year GS?

 

P.S. The mounting bracket from the 1998 ABS module was definitely different from my 1999 ABS module bracket. The numbers on the side were also different. I still would think these should be the same without frying some electronics, right? I did find one on eBay with the same numbers on the side so I suppose I'll get that one so it should work the same but that still doesn't resolve whatever the issue is that wont allow the car to start.

 

The only mistake you made in the ABS Module replacement procedure is not disconnecting the batteries negative terminal before swapping the modules. I would start at the fuses then scan the vehicle for codes.

As far as the ECU's being interchangeable I would not go purely on the eBay seller. Contact LEXUS and get a part number on both a 98 and 99 and see if they are the same.

 

Yes, I didn't unplug the battery and figured the key in the off position would be sufficient just to unplug the module. Hindsight is 20/20. Sigh. I looked at the regular fuses under the hood but not under the dash yet. I don't know how to check the relays or fuses that aren't your standard looking fuse. Strange thing is I didn't see the fuel pump shutoff switch/fuse ... Anyone know where that's located?

When you say to contact LEXUS, who exactly do I call to get these part numbers? A local Lexus dealership and talk to the parts and service department?

 

Could hooking up the wrong ABS/VSC module have locked up the ECU? Someone told me this and said it have locked itself down and need to be reflashed now; however, the immobilizer light stops flashing when I put the key in the ignition so I figured it must be recognizing the key. I'm just wondering from any mechanics on here that would know more about this than I do.

 

Does the car try to start AKA crank? And by contact LEXUS I meant their parts department(s).


Not a mechanic but I have never heard of something like this causing anything to happen that creates a "lock up" type of situation. I say get a code scanner on it.

Maybe someone else will have some more insight

 

The car turns over just fine but just will not start. Again I used to hear some noise from under the hood which I always thought was fuel pump priming but now I don't hear anything. No blown fuses found and not sure about which relays may have gone bad or how to check them.

What kind of code scanner would I get? I've seen a few different places on the car where one looks like it can be plugged in. Is there a way to check without one by jumpering anything?

 

Does anybody know where the fuel pump shutoff switch is? I ripped apart the passenger side of the trunk liner and did not see it. Also, what about the EFI relay? I was thinking perhaps I can check that out with a multimeter.

 

I tested the Fuel Pump Relay, located down by the fused on the lower left, by swapping it with the horn relay. Still no fuel pump. I found something that said I could jumper the diagnostics port to see if the fuel pump would come on with B+ and Fp; however, I have no idea what pins that represents. Hopefully some searching will turn up some diagrams.

 

so you want to test if the fuel pump is working? have someone sit near the back seat and turn the key on and listen for it. or you can losen up the fuel pressure damper by the fuel rail and have someone crank over the engine to see if fuel is pumping out.

 

I just want to pinpoint what the issue is and since I don't hear the fuel pump going I thought it may be something to do with that.

I bought a new EFI relay since I could here it clicking when turning the key forward but couldn't tell if it was bad. That did nothing. The main fuse is fine. The relay under the lower left inside the car is fine. I checked a ECU fuse on the lower right which was fine. I removed the rear seat and found the fuel pump and vaporizer but no reset button. I did fine the Fuel Pump Relay back there. I was going to jumper the B+ and FB terminals on the diagnostics port under the hood but my car doesn't have any metal connector in the FB port ... go figure. I did notice those letters on the harness connecting to the Fuel Pump Relay back by the trunk and jumpered them but nothing happened. I did have 12v+ power coming to the B+ port back there when tested with a tester.

I've got no fuel pump action. I sprayed starter fluid in the throttle body while turning over the engine and it didn't even try to start so I'm guessing no spark either. I couldn't find spark plugs to pull the wire and test. I'm left with thinking the ECU is in some kind of lockdown mode where it's not sending signal to the fuel pump or spark. I don't know if sending it off for reflashing would make a bit of difference. I mean the red light goes off on the dash when I insert my key but perhaps this lockdown is the same thing that happens when you insert a key that's not registered to that memory (no spark no fuel?)?

If I send it off will they know if the unit is any good? I'm worried I'll send it off and they'll reflash my key but it could still have something fried in there? Man I was just trying to fix this light before I sold the car ... should have sold it as is ... SOB!!

 

Is there a way I can rule out the ECU on this issue? I mean how can I tell if the ECU is actually sending the correct voltage to the fuel pump relay, EFI, or however this system is supposed to work? And how can I tell if I have spark when I cannot find any spark plugs?

I'm just really wondering how it could be the ECU when I hear the EFI relay clicking and I have 12v+ back at the Fuel Pump Relay. Also, how do I do the jumper test to bypass the ECU and kick in the fuel pump on a 1999 GS300 when I don't have any connector on Fb on the diagnostics port under the hood?

 

You should start searching the forum for answers to some of these questions. HERE is some info on testing the fuel pump for instance.

There is also a sticky DIY with a LOT of info including how to change the spark plugs (which will show you how to access them) HERE.

Based on all the info you already provided above I still say check the engine DTC's with a scan tool. Personally I would not fool around with jumping wires at this point. If you don't have a code reader see if a local auto parts store lends/rents/sells them. If that is not an option see if a local mechanic may be willing to stop by and pull codes for you, possibly for a charge of course but simply pulling codes at your house is NOT the same as diagnosing the issue at a shop and not labor intensive so don't get hosed on the cost of this.

You can also start in on the fuel pump. Check resistance per the link above. Check the terminal for corrosion.

After that it may be time to get a professional technician involved in diagnosing the issue for you in their shop. This is a sucky situation and I feel for you on it. Best of luck and let us know the outcome or any progress you make.

 

I should add a higher end professional scan tool will be able to command the fuel pump on and off with its software making diagnosing it a lot easier.

 

Good luck, I feel your pain.