truck wouldnt start. balast resistor?

yotawheeler · 06-29-08, 10:07 PM

ok...so i went out to play a bit in a local quarry and came down off a rock pile and the truck was dead, made sure it wasnt out of gas and it still wouldnt start, turn but no fire. some guys came by who were more mechanically inclined then me and said it was the balast resister. once the bypassed it the truck would start but not idle, as soon as i was off the key it died. i made it home by keeping the key turned (home was only about 5k) but im not sure what they did to bypass the resister...anybody have any ideas?

Dirtsquirt · 06-29-08, 11:06 PM

My 40 has no ballast resistor. It has a coil with an internal resistor
It is my understanding 40's didnt have ballast resistor as the coil
has the internal resistor

Are you saying you had to hold key so the starter was turning the
entire way home?

yotawheeler · 06-30-08, 12:10 AM

mmmm well yea i guess it would have been, the key was turned in the start position, if i let off of it the engine would die. this was just an extremly temp thing to get me home and out of the quarry that i was in. the truck has not been driven since i got it home...i need to get it sorted out before i drive it any more

bsmith123 · 06-30-08, 05:19 AM

you have two routes for wiring to your coil + side one through the ballast resistor, another that applies a full 12 volts during start

you were using the start pos and bypassing the BR --sounds like they didn't do anything

to make it run ---temp run a wire from your batt to the + side of the coil but fix it as soon as you can

Dirtsquirt · 06-30-08, 07:46 AM

I couldnt find a diagram for your specific year online. but I did find one for an earlier year.
http://www.ih8mud.com/tech/72fj40-wire/71fj40_wire.gif

according to this you have 1 wire to the positive. (excluding ACC
like Pertronix or Tach.)

I am gonna say it sounds to me like your ignition switch has taken "a
turn for the worse".

A test light or a vom should easily diagnose this. If it is consistent
Turn the key to run position. ie one click to the right from key removal position
Check for 12v at the IG (ignition) terminal on the back of the
Key switch, Start Switch etc. the Print calls it the Ignition Switch.

Good luck

Pin_Head · 06-30-08, 09:42 AM

Your problem is consistent with a bad ballast resistor. The starter motor has a wire to bypass this resistor during starting so that full voltage is applied to the coil when the battery voltage drops due to the starter motor turning.

Get a new one. They are a couple of dollars at NAPA and they are generic.

As noted above, you can temporarily bypass this resistor (so you don't burn out your starter motor) by moving the hot wire from the ballast resistor to the coil + post. If you run it like this continuously, the coil will overheat.

Toyota used ballast resistors on cruisers throughout the 70s.

FJ40Jim · 06-30-08, 10:02 AM

BR was factory spec on 73-77 USA trucks.
78-80 models w/ elec ignition got a resistor wire in lieu of an ceramic resistor.

On a 74, power for the ignition is supplied by a dedicated fuse. So it sould be as simple as a bad fuse.

yotawheeler · 06-30-08, 07:14 PM

wicked. thanks for the help guys....iv been kind of looking at it trying to figure out what the guy did and im still not 100% sure but ill get the BR tomorrow. the local parts guy is into old school chevs so he is pretty good about helping me out

tlc_4play · 07-01-08, 03:41 AM

Did some research

A ballast resistor is only required if the resistance of the coil primary is less than 2.5 ohms.
example; my Pertronix Flamethrower 12V coil has a primary resistance of 1.5 ohms, therefore the installation of at least a 1.0 ohm ballast resistor is recommended to limit the current and prevent overheating the coil when doing slow 4wheeling (+/-1500rpm)

yotawheeler · 07-01-08, 07:30 PM

got 'er going...thanks guys!

06-29-08, 10:07 PM	#1
yotawheeler IH8MUD Addict Join Date: Apr 2006 Posts: 801	truck wouldnt start. balast resistor? ok...so i went out to play a bit in a local quarry and came down off a rock pile and the truck was dead, made sure it wasnt out of gas and it still wouldnt start, turn but no fire. some guys came by who were more mechanically inclined then me and said it was the balast resister. once the bypassed it the truck would start but not idle, as soon as i was off the key it died. i made it home by keeping the key turned (home was only about 5k) but im not sure what they did to bypass the resister...anybody have any ideas? __________________ in my driveway.... '74 FJ40- disc brakes, saginaw,8274. SM420 sitten in the shop just waiting '78 FJ45 project rig x2 '81 BJ42 '86 HJ60

06-29-08, 11:06 PM	#2
Dirtsquirt IH8MUD Junior Join Date: May 2008 Location: Spokane Wa. Posts: 143	You got me. My 40 has no ballast resistor. It has a coil with an internal resistor It is my understanding 40's didnt have ballast resistor as the coil has the internal resistor Are you saying you had to hold key so the starter was turning the entire way home? __________________ 1970 fj40 f engine 3sp w/floor shift 2.5 procomp lift 32" AT tires, Warn Bellvue winch. Evolution Blog http://dirtsquirtfj40.blogspot.com/

06-30-08, 12:10 AM	#3
yotawheeler IH8MUD Addict Join Date: Apr 2006 Posts: 801	mmmm well yea i guess it would have been, the key was turned in the start position, if i let off of it the engine would die. this was just an extremly temp thing to get me home and out of the quarry that i was in. the truck has not been driven since i got it home...i need to get it sorted out before i drive it any more __________________ in my driveway.... '74 FJ40- disc brakes, saginaw,8274. SM420 sitten in the shop just waiting '78 FJ45 project rig x2 '81 BJ42 '86 HJ60

06-30-08, 05:19 AM	#4
bsmith123 IH8MUD Lifer Join Date: Oct 2007 Location: panhandle florida Posts: 1,043	ballast you have two routes for wiring to your coil + side one through the ballast resistor, another that applies a full 12 volts during start you were using the start pos and bypassing the BR --sounds like they didn't do anything to make it run ---temp run a wire from your batt to the + side of the coil but fix it as soon as you can __________________ B Smith123 Chaos, panic, & disorder - my work here is done. The easy way ain't cheap and the cheap way ain't easy!!! 71 FJ frame off build "UGLY BETTY" 33 in BFGs, 4 inch HFS lift, Durabak lined tub, and a soft top in a box! Now sportin a 2F and 4 speed

06-30-08, 07:46 AM	#5
Dirtsquirt IH8MUD Junior Join Date: May 2008 Location: Spokane Wa. Posts: 143	Hmm I couldnt find a diagram for your specific year online. but I did find one for an earlier year. http://www.ih8mud.com/tech/72fj40-wire/71fj40_wire.gif according to this you have 1 wire to the positive. (excluding ACC like Pertronix or Tach.) I am gonna say it sounds to me like your ignition switch has taken "a turn for the worse". A test light or a vom should easily diagnose this. If it is consistent Turn the key to run position. ie one click to the right from key removal position Check for 12v at the IG (ignition) terminal on the back of the Key switch, Start Switch etc. the Print calls it the Ignition Switch. Good luck __________________ 1970 fj40 f engine 3sp w/floor shift 2.5 procomp lift 32" AT tires, Warn Bellvue winch. Evolution Blog http://dirtsquirtfj40.blogspot.com/

06-30-08, 09:42 AM	#6
Pin_Head IH8MUD Lifer Join Date: Feb 2002 Location: OC, CA Posts: 5,260	Your problem is consistent with a bad ballast resistor. The starter motor has a wire to bypass this resistor during starting so that full voltage is applied to the coil when the battery voltage drops due to the starter motor turning. Get a new one. They are a couple of dollars at NAPA and they are generic. As noted above, you can temporarily bypass this resistor (so you don't burn out your starter motor) by moving the hot wire from the ballast resistor to the coil + post. If you run it like this continuously, the coil will overheat. Toyota used ballast resistors on cruisers throughout the 70s.

06-30-08, 10:02 AM	#7
FJ40Jim Cruiser Curmudgeon Join Date: Sep 2003 Location: Lancaster, Ohio, USA TLCA# 1914 Posts: 3,160	BR was factory spec on 73-77 USA trucks. 78-80 models w/ elec ignition got a resistor wire in lieu of an ceramic resistor. On a 74, power for the ignition is supplied by a dedicated fuse. So it sould be as simple as a bad fuse. __________________ Thanks, Jim C. TLC Performance Underhood Janitor, cleaning up other people's since 1988.

06-30-08, 07:14 PM	#8
yotawheeler IH8MUD Addict Join Date: Apr 2006 Posts: 801	wicked. thanks for the help guys....iv been kind of looking at it trying to figure out what the guy did and im still not 100% sure but ill get the BR tomorrow. the local parts guy is into old school chevs so he is pretty good about helping me out __________________ in my driveway.... '74 FJ40- disc brakes, saginaw,8274. SM420 sitten in the shop just waiting '78 FJ45 project rig x2 '81 BJ42 '86 HJ60

07-01-08, 03:41 AM	#9
tlc_4play IH8MUD Junior Join Date: Aug 2006 Location: Jhb - South Africa Posts: 87	Did some research A ballast resistor is only required if the resistance of the coil primary is less than 2.5 ohms. example; my Pertronix Flamethrower 12V coil has a primary resistance of 1.5 ohms, therefore the installation of at least a 1.0 ohm ballast resistor is recommended to limit the current and prevent overheating the coil when doing slow 4wheeling (+/-1500rpm) __________________ 1999 - FZJ105 1979 - BJ-FJ40

07-01-08, 07:30 PM	#10
yotawheeler IH8MUD Addict Join Date: Apr 2006 Posts: 801	got 'er going...thanks guys! __________________ in my driveway.... '74 FJ40- disc brakes, saginaw,8274. SM420 sitten in the shop just waiting '78 FJ45 project rig x2 '81 BJ42 '86 HJ60

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