where did my 12 volts go?

[broncosami]

OK here goes, then 1984 ranger 2wd 4cyl. manual trans. Now sits on a 74 bronco chassis w/ a carb 5.0, AOD 4x4, tilt bed and tilt front end too. I started and ran this many times in the shop. recently became hard to start, now wont start at all. That's background on truck, now problem. I have no VOLTAGE to the starter. I have continuity from the red with light blue wire at the ignition through the old clutch switch to the starter, so that's all good. I replaced the ignition switch also. I have 12 volts on the two big yellow wires to the switch, and to several of the contacts on the switch. I can take the switch out and check it for continuity and now where is there any position where there is continuity between the power contacts and where the R/LT BL wire goes. The prints I've seen say that's what I should have there. Both switches I have ring out the same and I've gone back to parts store and those check the same also. Everything else works fine but I don't know where the 12volts went. I'm not sure if I'm to get the 12volts from. There is no continuity from that red/ blue contact to ANY other contact on the switches. So where does it come from? IT wont start, and my 4yr old boy wants to hear HIS dump truck start. I'm lost at this point.

 

[RonD]

First check the Battery Negative cable going to the engine block, there is no 12v if there is no 0v(ground).
Should be a ground strap to rad support, fender well and from engine to firewall, no 0v means no power.

Starter relay on fender well should have 3 posts, 2 larger ones and 1 smaller labelled "S".
(if you have a 4 post relay then the "I" post will got to the ignition coil(spark) "+" terminal.)

The "S" post is for the wire that comes from the Clutch switch, it should have 12v only when key is turned to START(crank), when there is 12v here the relay closes and sends battery 12v to starter motor.
Also make sure starter relay is bolted to fender well, no rust, the bolts are the ground for the relay so need to be clean to work as a ground.

The 2 larger posts are for the Battery Positive and Starter Motor's large cable.

Battery positive post will have one or two other wires connected, these are for the alternator and "power out" to fuse boxes.

Starter motor post will just have the 1 wire to starter motor.

 

[snake]

I got lost in the explanation, but you should have a big wire from the battery to the solenoid switch on the fender. Check for 12V there. Then it should go to the starter. You can hotwire the solenoid with a screwdriver if you have 12V at the solenoid. Check all the grounds also. I hope that helped, your problem sounds more complicated than I'm thinking...

 

[huh?]

clutch pedal depressed when testing continuity from switch to end of red/lt. blue?

 

[broncosami]

Thanks for looking and replying. My problem is deeper than that I'm afraid. I can jump the starter with a screwdriver and it jumps. I have voltage there from the Battery. I have 12volts at the ignition switch. I have continuity from the switch all the way to the starter through the "jumped out" clutch pedal switch. That's the red/lt. blue wire, its all good. I don't use a relay on the fender I have one on the starter only. This all worked fine for me. Im not getting voltage out of the ignition switch. The radio,lights, air compressor, and accessory water pump all work. I have a Holly fuel pump that's wired to the run circuit .that works also. I have my large cable bringing 12volts to the starter. I have 12volts going into the ignition switch. I don't have 12volts coming out of it to the starter relay. I do have 12 volts going out to several other circuits. I have two ignition switches I've been trying to use in place and both do the same thing Maybe this helps.

 

[adsm08]

Resistance test is not conclusive proof that a wire will carry current. Resistance can test good and the wire only be hanging on by a single strand.

Voltage drop or load testing would be the next step at this point.

Voltage drop consists of powering the circuit, and then testing voltage with the positive lead on the supply side (at the switch in this case), and the other at the load end (the starter relay). The number gotten is the voltage lost along the trip.

The load test would involve hooking up a known good dummy load, I recommend a headlight, to the wire to be tested, and then power it up. See if it works your test load.

 

[black_demon69]

Resistance test is not conclusive proof that a wire will carry current. Resistance can test good and the wire only be hanging on by a single strand.

Voltage drop or load testing would be the next step at this point.

Voltage drop consists of powering the circuit, and then testing voltage with the positive lead on the supply side (at the switch in this case), and the other at the load end (the starter relay). The number gotten is the voltage lost along the trip.

The load test would involve hooking up a known good dummy load, I recommend a headlight, to the wire to be tested, and then power it up. See if it works your test load.

me agrees 100%

 

[broncosami]

I agree also, the old voltage but no current rule. I am working a ton of hours till Friday then should have Friday off. Ill try that test with the headlight then. If that works Ill try to bump the starter with it. However lets not forget I have no voltage coming out the ignition switch at the red/ lt. blu contact. That's where the power to the starter would come from. Let me know if you think of anything else for me to try. Thanks for the advice.

 

[huh?]

...Now sits on a 74 bronco chassis w/ a carb 5.0, AOD 4x4, tilt bed and tilt front end too.

what dummy asked if clutch pedal was depressed when testing?

Originally Posted by huh?:
clutch pedal depressed when testing continuity from switch to end of red/lt. blue?

oops, heh heh. so much for reading carefully. sorry, my bad.

how about adding one more modification to your truck? something along the line of a push button and a brand new wire to the starter.

 

[Scrambler82]

I have read these postings a few times through just to try and understand what is going on.
I know I am a little slow on the uptake but it shouldn't be this difficult to understand on a carb'd 302.
Are we interested in starting the truck or power to the ignition switch in the dash .

broncosami, simple as you can explain what you are after ?

Power,to the starter is through a solenoid usually mounted on the fender well but the newer high torque starters are setup with the starter mounted solenoids, which do you have ?

Problem with fender well mounted solenoids is bad grounding, remount it with cleaned up mounting holes and some bare metal and conductive paste behind it. Through bolts are good too with HD external tooth lock washers.
Make sure all of your connections are CLEAN and tight, tight alone is not always good enough.
The starter too needs a good ground to perform, the better the ground system the better it will operate. If and when you ever redo the grounding system, run an extra ground wire, 3 or 4 gauge, to the top mounting bolt of the starter. A solenoid ground wire isn't a bad idea too.

After that if the solenoid is not clicking then you have no power from the ignition.

Trace the wire back to the ignition, if connected and not damaged and no power coming out of the ignition at the solenoid connector, then attempt to jump that wire with the power feed from the battery. If the solenoid does not clicks then the ignition has a problem, if the solenoid clicks then you need to readdress the starter, power, ground, is it any good ?

When you turn the ignition to the start position most of the power accessories positions on the ignition do not have power on them so that maybe where you are, I'm not sure.

Another thing... Get rid of the clutch switch, jump it out. If you are ever in need of a jump the clutch switch will prevent it.

If this post is in the obvious either delete it or think things through a little more. Older vehicle DC systems are straight forward.

 

[broncosami]

OK, got it. I realized I was checking the switch with it in the RUN position not the start position. I was explaining how the switch works to a friend when I figured out my error. The switch has springs you need to compress to get the contacts to go to the START position. I the installed the switch in the column and tried it for 12volts to the starter. It was there, yeah . I put a head light to ground at the end of the starter wire to ground. The head light came on, so I have current. Then tried to start truck and it wouldn't start yet. I charged the Battery over night. Next day starter clicked but not start. So, I ran a jumper wire from where the clutch switch used to be to the starter. I tried that and had about 400hp fire up!!! Seems like the old "red/ Lt. blue wire from the clutch to the starter has an issue somewhere. Im going to run my own wire to replace it. NOW I have the truck starting with the key the way I wanted it to do. Thanks to all that replied.