Lexus wil not turn over,after putting positive cable on nagative post.could the problem be the starter relay?

It sounds to me that the small post or wire going to the starter is touching the large wire. The large wire is the positive battery cable and the small wire is the signal wire from the ignition switch. If the two are touching each other the starter will engage as soon as power is applied and circuit is completed at the battery.

Clean your fuse block by hand carefully or replace it. Corrosion is not always visible.

Locate your starter and with the vehicle in park have an assistant hold the key in the crank position while with a test light you check for power at the posts on the starter solenoid. One post shoul have power from the battery, the other from the ignition switch and the other should supply power to the starter motor. Make sure your battery is in good shape and fully charged. If all you get is a click from the solenoid then it's likely that you need a starter. If no power fom battery check battery and positive cable/connection for integrity and tightness. The small post is power from the ignition switch if no power her with the key on the crank position check fuses, park/neutral safety switch and it's related wiring.

IF STARTER RELAY BAD THE STARTER WONT MAKE NO NOISE AT ALL HEADLIGHTS WONT DIM.IF YOU CLICKING NOISE BATTERY VOLTAGE TOO LOW. MAKE SURE BATTERY VOLTS ARE 12.6 VOLTS AND USE TEST LIGHT TO SEE IF STARTER GETTING POWER.COULD HAVE BLOWED IGNITION FUSE OR FAULTY IGNITION SWITCH. TO CHECK STARTER SOLENOID FIRST TURN OFF RADIO THEN REMOVE NEGATIVE BATTERY CABLE AND POSITIVE BATTERY CABLE.THEN REMOVE STARTER BUY A REMOTE SWITCH.YOU NEED BATTERY JUMPER CABLES HOOK BATTERY JUMPER CABLES TO BATTERY PUT POSITIVE CABLE ON POSITIVE BATTERY POST THEN PUT NEGATIVE BATTERY CABLE ON NEGATIVE POST. HOOK BATTERY CABLES TO STARTER USE NEGATIVE CABLE GROUND STARTER BODY AND PUT POSITIVE BATTERY CABLE ON THE LARGE POSITIVE POST ON STARTER SOLENOID. NOW TAKE REMOTE SWITCH HOOK RED WIRE TO STARTER SOLENOID POSITIVE POST THEN HOOK BLACK WIRE TO REMOTE SWITCH TO STARTER SOLENOID SWITCH TERMINAL WITH LETTER S THEN PRESS REMOTE IF STARTER SPINS STRONG WITH A GOOD KICK STARTER GOOD.YOUR PROBLEM COULD BE CORRODED WORN BATTERY CABLES. WEAK BATTERY FAULTY IGNITION SWITCH. IF STARTER DONT WORK WHEN YOU PRESS THE REMOTE SWITCH STARTER SOLNOID BAD OR STARTER ITSELF BAD.IF ALL IS GOOD. CODE SCAN CAR FOR THEFT SECURITY FAULT CODE.

hi, i think you have put the MAIN HEAVY CABLE direct to the STARTER MOTOR on the SOLINOID. this will keep the starter motor running. take battery lead NEGATIVE CABLE OFF the BATTERY, and change the MAIN HEAVY CABLE from the SOLINOID terminal to the other MAIN terminal on the SOLINOID and NORMALLY it SHOULD go with a SLIGHTY (smaller cable this GO'S to the FUSEBOX rest of car POSITIVE FEED). the other small wire is the solinoid START WIRE. the solinoid has 2 circuits the first circuit is HEAVY BATTERY LEAD to 1 terminal on the solinoid. the other side of the solinoid HEAVY CABLE to STARTER MOTOR. this is only 1 side of the SOLINOID (THIS IS A VERY VERY HEAVY SWITCH). the other side of the SOLINOID is the START SIDE (REMOTE CONTACT) of the SOLINOID, by turning the IGNITION KEY to STARTER POSITION, this operates the SOLINOID. this makes contact to run the starter motor. once the connections are done REPLACE NAGATIVE BATTERY LEAD and start the car. gerry

If auto, did you check the neutral safety switch? If stuck open, car will not start.

Turn key to the run positio, Press on your brake and run your shifter through the gears a couple opf imes then try starting in neutral. This is for the benefit f the neutral safety switch. If still nothing , Raise the hood and and check the battery for a bad or corroded connection. If all is good, make sure car is in park. There is on the driverside fenderwell a relay that looks like a mine Roun With two small terminals and tw large terinals o opposite ides.. When you turn to crank, you put cirrent to one of the small ter minals and that causes the two large battery cables to connect and give power to the starter. If you can jump the battery side cable and the starter side post the starter will crank if nothing is wrong withe the starter.the two large posts. Use a jumper cable,NOT a coat hanger, iF THE STARTER SPINS THEN START IT WITH THE KEY. Good Luck.. Any more help let me know.

Follow the positive cable from the battery to the relay. From the other side of the relay follow the large wire down to the starter.

You may have corrosion inside your battery cables or a loose connection somewhere.

If you have a voltmeter connect one lead to the POSITIVE post of the battery and the other to the POSITIVE post on your starter while you have a friend crank the engine
WATCH YOUR HANDS!

This is called a voltage drop test and you should see less than 0.5v on the multimeter while you are trying to start it, if you have high resistance (corrosion bad connections) you will see a higher voltage. 0.5v is the MAX you should see.

Do the same test on the ground side of the circuit, connect to the NEGATIVE battery terminal and the starter case, your voltage reading should be 0.1v or less

hi from uk the starter relay you mention ? in uk we know it as the starter solenoid which is fixed to starter motor and has the positive cable from battery attached along with a thinner cable which provides elec's for cars fuse/other relays box the problem you mention may ? be the thin wire (not cable) that connects to solenoid near the other cables it will have either spade or round push on connector this wire is the wire from ign switch that when key start position is selected it energises the solenoid and main starter rotates to start engine so in effect? you are near by calling it a relay as it is a heavy duty relay make sure this wire is secure and free from corrosion hope you now understand function of starter ? best wishes