What is the correct amperage to ignition switch on 88 gmc k1500

The problem is at the starter motor solenoid. The clicking sound heard is the solenoid switch engaging but with not enough force to switch on the heavy current needed to turn the starter motor. Light tap with a soft mallet on the starter motor might help but the starter motor need to be serviced to replace or service worn/burnt/dirty the heavy duty solenoid switch.

Hi Kevin it sounds to me like your solenoid that is attached to your starter motor needs replacing had this with a ford cortina mk 5

If "tapping" the SOLENOID ever worked... you
HAVE A DEFECTIVE SOLENOID.

Defective is all inclusive... and when "STUFF"
happens (burns up)... it is VERY LIKELY to cause
COLATERAL damage...

(FRIED WIRES & IGNITION SWITCH)
((fix that "STUFF" later)).

At the SOLENOID ... apply "B" battery DIRECTLY
to the "S" terminal of the SOLENOID...

IF it does not fully spin up the starter 100% of the time
the solenoid or the starter is DEFECTIVE.

If it won't crank over, it's a problem in the starting circuit, not the ignition circuit. Check your battery and starter for clean, tight connections. Listen for that click to see if it comes from the starter solenoid on the starter-maybe have someone try to start it while you watch and listen under the hood. If the click is from the solenoid (and not from the starter relay), then the starter is not getting full battery power to crank (bad connection), or the starter needs to come off and be tested.
If the click is from the starter relay, you could pull off the little purple wire to the starter solenoid and see if it has 12 volts when the key is in start position. If you have power there in cranking position on the switch, the solenoid is bad or the starter may be the problem-again, it will have to come off for testing. If you have no power at the solenoid in cranking position, the circuit from the ignition switch to the solenoid is not working. The start relay and the neutral safety switch (or clutch switch if manual transmission) are in the starting circuit from ignition switch to the starter solenoid. Good luck.

does it turn over or does it do nothing at all

check alternator output at the alt and at battery also put a test light on the starter solenoid at the little wire on solenoid see if it lights up when turn key ? possible positive or negative cables have good ohm checks but not carrying enough current ?

If you have tried a boost.......even though the lights and radio work and hear a click when turning to start......it may need a starter.
It would be best to check for voltage to the starter and from the smaller wire at the starter solenoid when turning the key to start position before replacing the starter.
With the truck in park or neutral....jump the starter solenoid from under the truck......with no cranking from the starter under these conditions....yes...... you may need a starter.

If you do not get a voltage reading at the smaller wire at the solenoid when the key is in start mode....check the wiring,starter relay,the safety neutral switch and the ignition switch.
If you have anti theft.........this may cause a no start too.

sounds like starter solenoid,try cycling the ignition on start on start repeatly but do not go back to the off position off on start will activate the fuel pump repeatly and might flood it,with a faulty solenoid you can usually cycle the ignition repeatly and it will finally engage the starter

tap the solenoid on the starter probably a bad starter solenoid.

the starter should be replaced. The solenoid is kikcing the pinion out but there is no contact being made to turn the starter motor. I have the exact same truck and before i changed the starter used the old starter tap trick. Tap the starter casing with a hammer and it should start turning again. hope this was helpful for you. Good luck.