Gen 1 light

[cucvrus]

I have an 86 M1009 that the generator 1 light is on dimly when idling. It gets brighter with throttle. It is not my truck I am trying to help someone out with it. I replaced the Gen1 to no avail. The replacement rebuilt alternator does the same thing. Another thing is the truck goes all the way up on fast idle when started cold. I disconnect the green wire to the fast idle solenoid and it returns back to normal. Plug it back in and it will idle normal again. And not every time. It started this morning was on normal fast idle and kicked down as it is supposed to do. This afternoon I started it and it went up half way but not all the way like it did yesterday. Any ideas. I looked at the TM's and they were vague. I may be missing something. I have worked on these for many years and this one has me stumped at this time. Any ideas?

 

[cucvrus]

Alternator problem solved. I should have done it myself. I told the guy left alternator. Well he changed the left alternator. Left one while you are standing in front of the truck. Problem solved with the alternator. Now it has 2 rebuilt alternators on it. With the heavy solid pulleys. The other pulleys were the stamped steel ones and were pitted and rough looking. New Gates belts installed. Also contributing to the dim and flickering Gen 1 light was the blower switch. I still need to resolve the fast idle switch. Is that fast idle switch/motor a common part that is available at a parts store?

 

[dmetalmiki]

The solution sometimes comes with investigation perseverence and self dianosis. You seem to have achieved that. So well done.

 

[cucvrus]

What is the correct name for the fast idle motor/solenoid on the injection pump?

 

[antennaclimber]

I found the fast idle switch and the solenoid on Amazon.
Search for
ACDelco 10154649
ACDelco 14066255

 

[doghead]

I look at the parts TM when I need part numbers and correct nomenclature.

 

[cucvrus]

Good for you. I looked could not find it. Why is that the only answer you ever have doghead? Look at the TM's. Thank you Antennaclimber for a decent answer. They are a bit pricey. I had better make sure that is the issue. I may just take it off another engine I have lying about. I never saw one act so intermittently work 99% of the time. Only foul up the other 1%.

 

[Barrman]

The green wire has two ends at the IP. The cold start timing advance inside the pump and the fast idle solenoid on the outside. The other end of the green wire is on a switch/sensor located at the passenger side rear of the passenger side head. That part gets power anytime the key is turned on. The green wire is supposed to only be energized if the coolant temperature is below 95 degrees.

The fast idle solenoid is a very simple and weak coil with a shaft running through it. The little bitty windings will break if you look at them wrong. It also will not advance the throttle by itself. You have to turn on the key and then push the pedal down to let it move and hopefully hold the fast idle position.

So, if you are getting power to both green wire leads at the IP, moving the throttle like the sticker on the sun visor in front of the driver says, the engine is cold enough to turn it on and it is working correctly. You will get a 200 rpm faster idle.

I have 4 6.2 powered vehicles that get driven pretty much daily. One of them has a fast idle solenoid with an attitude. As in some mornings it works as intended. Other mornings the starting knocks it off and I have to ease throttle in until I feel it catch again. Other mornings the after glow might knock it off. This is the only true totally 12 volt truck I run and I think that is some of the issue.

I have cleaned and lubed the fast idle solenoid. Cleaned all leads associated the the green wire including replacement of the sensor. I just live with it now. My suggestion is to make sure all parts are doing what they are supposed to. If they are, then make sure you are doing what you are supposed to.

If you and the machine are both doing as required yet the fast idle is still erratic. Maybe there are some fuel filter, return line or IP issues you don't know about?

 

[cucvrus]

Thank you for the excellent explanation Barrman. This is the only vehicle that I have encountered this issue with. I am going to spray the fast idle motor with some dielectric spray and give it a try. It started for me every time I tried. I want to give it back to the owner tomorrow. Thank you again.

 

[dstang97]

Those high idle switches very rarely need to be replaced, but They may need to be repaired if that helps. There are a bunch of threads on repairing them. They are simple to repair.

 

[cucvrus]

Come on man fill me in more. I need to repair this. I cleaned it up good and sprayed it with sea foam deep creep. Is that part of the repair process?

 

[dstang97]

Pretty much all you do is find the broken end and build it up with solder so it makes a complete circuit.

 

[timarr]

Check the switch on rear passenger head. It controls the fast idle rod. Napa TS7265. Its 39 bucks, everywhere else 100 bucks!

 

[cucvrus]

I think I covered the sticking idle switch. It was a little dirty and dry. The sea foam deep creep seems to be working. It is a little smoother and don't seem to stick now. Thanks for the tip. But it is engaging. Sometimes just to much.