rholt12

About 8 months ago my check engine light appeared. upon checking no codes ever showed up. I continued to drive the car with no issues other than the check engine light. Then about 2 months ago I started to have difficulty starting the car, the engine would turn over fine but it acted as though spark was not getting to the engine after cranking a few times the car would start and run fine. Over time this problem grew more frequent until one day the car wouldn't start at all.

After my mechanic stopped by we were able to get the car to start by wiggling the radio noise suppressor connected to the driver side ignition coil. We switched out both the noise suppressor and coil with new components to find that the car still would not start. On reading through the forum my thoughts went directly to the ECU to which we took out and sent away to a company to test or repair. The ECU came back good but just to be on the safe side I purchased a second ECU from a working car to double check and both now are yielding the same results.

It appears that the pin out on both of the ECUs that sends electricity to the igniter were registering 1.7 volts instead of the 4.5 to 5.5 as needed. Upon sending the ECU in a second time to testing the company confirmed that while on the vehicle simulator the ECU does send out the required 5.1 volts from that pin. So this is where I am at now. The ECU is not the issue, 2 separate ECUs have created the same result.

It would seem that somewhere from the key to the ECU the correct amount of voltage or signal is not making it to the ECU to enable it to pass along the required voltage to the igniter. Has anybody seen something similar to this or have any ideas on what I should focus on?

Thanks

spuds

Bump.

rholt12

Im not sure if I am happy about solving the issue or mad I did not discover this before, but today after 2 weeks in the shop and countless hours of testing and swapping out ECUs it appears to have been the master key. After doing some more information digging, I went to the shop today with my valet key and the car started right up. So it would seem that the original master key lost its programming

spuds

Maybe same thing on my 98? My master also was non functional for starting car.

JohnAndic

Ouch, Bittersweet for sure. Good luck buddy.

spuds

Im wondering if the master key failure is a common thing on immobilizer cars?

Yamae

It's not common thing but it happens once in a while after decades. Working for electronics industry myself for many years, I have experienced data loss problems time to time. The immobilizer chip has a non volatile memory inside and it can't hold the stored data forever. Attached are the example of lost memory data of a TV signal generator called monoscope . As you see the face of the lower lion, he lost his right eye due to the reason that the non volatile memory used to draw the picture lost the part of face data.

dlcoffin

a quick way to say is, it's not the key itself that's at fault, but the memory in the immobilizer in the car. one other way of failure, would be the transmitter portion in the key head, somehow loses it's fixed frequency registration due to electronics' age, and then is not the frequency expected by the immobilizer, when it 'reads' the key. similar to RFID cards. the electronics in the thing are excited to life by the transmission of a power current inducted from the reader, and then in turn send back the proper frequency for ID. otherwise, it's powered down, not having a current sent to it. even the wireless charging bases for mobile phones, similar methods.

rholt12

Help again is needed on how to proceed. As I stated before once I discovered that the Valet key started the car, the guys at the shop proceeded to put the car back together and now the valet key is doing the same thing as before. No spark and No fuel, same as before this indicates that the immobilizer is kicking in preventing the car from starting. This seems highly unlikely that another key would go bad in such a short time.

1. The immobilizer has gone bad. the 1997 is the year when they used a separate immobilizer module.
2. The transponder amplifier in the steering column has gone bad.

both are very expensive new and considering Ive already spent for than $1000 just to be in the same spot I was 6 weeks ago I am wondering if I can get a used immobilizer and have keys reprogrammed or Ive seen aftermarket devices that completely bypass the immobilizer but once again this is the year with a separate module and wiring a device to bypass might be very complicated leading to more problems in the future. any and all advice is appreciated

sdls

I had it happen before on a Honda that sat for years. Went to start it and it only cranked a million times without starting. On a hunch I opened the ECU and tore off the immobilizer SIP IC and voila, it started again.

rholt12

Now my only other key that worked, the valet key, is now doing the same thing as the master. Isn't it unlikely that both keys would go bad in such a small window of time. I'm thinking its either the transponder amplifier in the steering column or the immobilizer module. My question is how do I go about testing to find out where the problem is, the keys, amplifier or the immobilizer. Thanks in advance

spuds

The immobilizer transmitter around the ignition key lock should be dirt cheap and common at junk yard and is very easy to access.Its in this thread

https://www.clublexus.com/forums/ls-...ack-maybe.html

plexus914

Good luck.

rholt12

OK, I now believe I have gathered enough information to begin round 3. My car has now been down for over 2 months and well over $1200 spent with no resolution. Thanks to RA40 and Yamae and Plexus914 for your info. In order to help others if these issues I am going to document as much as I can. These are the steps we are going to take next week. if anyone sees somthing I have overlooked please feel free to comment.

1. unplug and disconnect the aftermarket radio, pull fuse and make sure no connection from the car to this radio

2. Get a used engine fuse box and replace the one currently in the car. unscrew the old one and plug in the new one while inspecting wires and connections to see if there are any issues.

3. check voltage regulator and record the VCC line going to OBD and ECU ( im going to have to do some homework to find out what the optimum voltages are, but recording the current values now )

4. follow the Lexus engine immobilizer system troubleshooting flowchart and respond to any codes associated with it.

hopefully the solution/fix will present itself before the list is completed but I think this is the most logical way to go about this. The guys doing the work are always busy and once I get into an available bay I need more than just, try this or try that. I need to provide them with a plan and since time is money that plan needs to logically arranged. Wish me luck

spuds

Good luck.