Fuse box

  • 1992 LEXUS LS 400
  • 4.0L
  • V8
  • 2WD
  • 200,000 MILES
I believe there is a short in my fuse box. I have power to the starter from the big wire but none from the little wire. I have tested the fuse box and when I turn my car to the start position my test light does not lite up.
Do you
have the same problem?
Wednesday, June 20th, 2018 AT 7:43 PM

1 Reply

Hi and thanks for using 2CarPros. Com.

First, I am not 100% sure I know where you are checking for power. Chances are there is a problem with the relay or the starter solenoid itself. On the starter, the big wire goes directly to the battery, so it will be hot all the time. The smaller wire should get 12 volts only when the key is in the start position. Test that first. If there is power present at the solenoid and the starter does not engage, the starter is most likely bad.

Next, the starter relay should be tested. The first two pictures are of its location and the third pic is testing the relay.

Here are the directions for testing:

Using an ohmmeter, check for continuity between terminals 1 and 3, Fig 5.
Ensure there is no continuity between terminals 2 and 4.
If either test fails, replace relay.


Here is the relay operation test. Pic 4 correlates with these directions.

Relay operation test:
Fig. 6 Relay operation test connection locations
Apply battery voltage across terminals 1 and 3, Fig 6.
Using an ohmmeter, ensure there is continuity across terminals 2 and 4.
If no continuity exists, replace relay.


Another item that can cause this type of issue is the neutral safety switch. If that is the case, often times the vehicle will start in neutral but not park, so try that. If you find the switch is an issue, it is adjustable. Pics 5 and 6 relate to location and adjustment.
Here are adjustment directions.

If the vehicle starts at any position other then N or P range, loosen neutral start switch attaching bolt and position shift lever in N range.
Align groove and neutral basic line, Fig. 10 then torque switch attaching bolt to 9 ft. Lbs.


If the switch needs replaced, here are the directions. Pic 7 relates to these directions.
Disable airbag system as described under maintenance procedures/airbag system disarming.
Raise and support vehicle, then remove front exhaust pipe.
Disconnect neutral switch electrical connector.
Remove control shaft lever, then remove lock washer and nut, Fig. 13.
Remove switch attaching bolt, then remove.
Reverse procedure to install. Rearm airbag as described previously.

I hope this information is helpful. I tried to think of different things which could be causing the problem. Let me know if it helps or if you have other questions.

Take care,
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Thursday, June 21st, 2018 AT 8:04 PM

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