| Author |
Message |
kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
|
 Posted: Thu Sep 26, 2019 1:07 pm Post subject: Ignition switch? Or starter? |
 |
|
My 412 automatic won't start! What you get when you turn the key is a humming sound around the ignition switch when you turn the key. No sound from the engine area at all. Battery is good; starter replaced a few years ago. This started happening now and again a year ago, but after a second of holding the ignition on it would turn over and start. This morning it just won't, no matter how many times I try. Just that humming sound.
Thank god the car's at home and in the garage; this could have happened anywhere. |
|
| Back to top |
|
 |
KTPhil 
Samba Member
Joined: April 06, 2006
Posts: 34013
Location: Conejo Valley, CA
|
| Posted: Thu Sep 26, 2019 1:47 pm Post subject: Re: Ignition switch? Or starter? |
|
|
| Is the humming the sound of the fuel pump? Do you hear the click(s) when you turn the key to RUN? Is it an automatic, and can you try bypassing the neutral start switch at the selector? |
|
| Back to top |
|
|
kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
|
| Posted: Thu Sep 26, 2019 6:30 pm Post subject: Re: Ignition switch? Or starter? |
|
|
| KTPhil wrote: |
| Is the humming the sound of the fuel pump? Do you hear the click(s) when you turn the key to RUN? Is it an automatic, and can you try bypassing the neutral start switch at the selector? |
Yes, I think it IS the fuel pump. It only turns on when the engine is running and/or when the starter is engaged. On a '74 412 with L-tronic FI.
Like I said, it was hinting at doing this every so often over the past year or so. I would engage the starter and get only the hum for a second or two, and then the starter would crank away. It makes me think the contacts in the ignition switch are shot. It's not the neutral switch in the shifter. |
|
| Back to top |
|
|
raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
|
| Posted: Thu Sep 26, 2019 6:41 pm Post subject: Re: Ignition switch? Or starter? |
|
|
Just to check.....this is common as the switch ages. Along with a little key tip wear....tbe key shaped hole in the gop of the nylon switch splits.
Im betting you are either hearing the pump or the key buzzer.
The quick check is to remove the small two screw plastic cover on the steering column shield and pull the plug off of the back of the ignition switch. Then plug in another switch and turn it with a screwdriver. If it starts up right you need a new ignition switch.
Ray |
|
| Back to top |
|
|
kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
|
| Posted: Thu Sep 26, 2019 8:50 pm Post subject: Re: Ignition switch? Or starter? |
|
|
Oh that's a great idea! I'll order a new switch and give that a try -before taking the steering wheel off and all the rest.
The key buzzer hasn't worked in ages. The soft "humming" only comes on when I turn the key to "start".
I used to have a 411 with D-Tronic FI, and the pump ran as soon as you turned the key on. But on my '74 412 I have the L-Jet, where the pump only runs when the engine is running - and I guess when you turn the ket to start it? Anyway, I'm virally certain that's what I'm hearing.
Thanks for your advice! |
|
| Back to top |
|
|
kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
|
| Posted: Fri Sep 27, 2019 12:24 pm Post subject: Re: Ignition switch? Or starter? |
|
|
I found a used switch in my parts cabinet and plugged it in like you said.
Same result: fuel pump engages when ignition is turned to "start", but that is all. I have no idea if this used switch is bad as well. But just in case it IS a good switch, what next should I look for? The starter is only 6 years old. Is there some kind of relay or fuse for the starter circuit? Could it be the starter after all? |
|
| Back to top |
|
|
raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
|
| Posted: Fri Sep 27, 2019 9:10 pm Post subject: Re: Ignition switch? Or starter? |
|
|
| kirk knighton wrote: |
I found a used switch in my parts cabinet and plugged it in like you said.
Same result: fuel pump engages when ignition is turned to "start", but that is all. I have no idea if this used switch is bad as well. But just in case it IS a good switch, what next should I look for? The starter is only 6 years old. Is there some kind of relay or fuse for the starter circuit? Could it be the starter after all? |
Ok...lift the drivers seat and look at the red terminal...about a 10 gauge wire...that is one a piggyback terminal to the positive cable. If its loose...this no start can happen.
Next...crawl underneath look at the long grey sheathed single wire to the starter coming from near the back seat. With age the sheathing shrinks up and pulls the wire loose. Ray |
|
| Back to top |
|
|
kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
|
| Posted: Thu Oct 03, 2019 9:30 am Post subject: Re: Ignition switch? Or starter? |
|
|
Well once again Ray is The Man!
I've been sick this past week and haven't felt like crawling under Sparkie, but I just did this morning. No obvious wire disconnected, but a small one that slides onto a prong was a little loose. I pushed it on tighter, slid our from under the car, crossed my fingers and turned the key.
VROOM!
Damn! Is that all it took?
I drove around the block, pulled back into the garage and turned it off. Turned the key once again and VROOM again!
so THANK YOU Ray for yet another Type 4 save of the day! |
|
| Back to top |
|
|
raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
|
| Posted: Thu Oct 03, 2019 9:48 am Post subject: Re: Ignition switch? Or starter? |
|
|
| kirk knighton wrote: |
Well once again Ray is The Man!
I've been sick this past week and haven't felt like crawling under Sparkie, but I just did this morning. No obvious wire disconnected, but a small one that slides onto a prong was a little loose. I pushed it on tighter, slid our from under the car, crossed my fingers and turned the key.
VROOM!
Damn! Is that all it took?
I drove around the block, pulled back into the garage and turned it off. Turned the key once again and VROOM again!
so THANK YOU Ray for yet another Type 4 save of the day! |
I cant tell you how many times that damn wire has done that to me!
What happens is that between the plastic insulator cap and a little corrosion that occasionally grows on the connector...the female terminal gets loose on the spade terminal.
I got tired of that crap...and took a short pigtail of the same wire and crimped a ring terminal onto it. I put the ring terminal on the bolt on the cable clamp so as long as the cable clamp is tight so is the ring terminal. I then connected the large red wire to a latching T-1 terminal about 3" away from the battery. I can still disconnect it in a snap...but now its not affected by the plastic cap or corrosion. Ray |
|
| Back to top |
|
|
|
