True expected glow plug voltage when WTS is on

[K9Vic]

OK, here is my question I know that the GP system outputs 12volts on both 24v and 12v converted systems. My M1010 is a 12v converted system and the resistor block is hooked up and shows 12v on both sides and 12v to the relay. When I unplug all 8 of my green GP wires the output when "wait to start" is on is 12v as it should be from what I have read here. However when they are all plug in the voltage is 5-6 volts, closer to 5 volts. I tried bypassing the resistor block but kept blowing the 40amp in-line fuse, but the resistor does output 12 volts, so I highly doubt that is the problem. I have all brand new GP and they are the AC 60G from local parts store.

So my question is, when "wait to start" is on, should all the GP have a true 12volts, or should it be like mine do to the load of them all on at about 5 volts? In this cold of about 30degrees my truck will start, but I have to cycle it at least 4 times to kick.

Thank you in advanced and this site has been a great help!!

 

[Blood_of_Tyrants]

The resistor block was put in to drop the voltage from 24 down to 12 (half of the voltage coming in). Your problem is that the glow plugs are not getting hot enough when the temp is low. When you convert to 12v, you should bypass the resistor. Do this and she will start first try.

 

[K9Vic]

The resistor block was put in to drop the voltage from 24 down to 12 (half of the voltage coming in). Your problem is that the glow plugs are not getting hot enough when the temp is low. When you convert to 12v, you should bypass the resistor. Do this and she will start first try.

I understand that and tried that, but when I did this I kept blowing the inline 40amp fuse I put between the battery and the resistor block (The TM said to use an fusible link, but I just used a inline fuse). Should it be a higher fuse, or get a fusible link cable? Also the voltage is 12volts out from the resistor block, if it is designed to down steps 24v to 12v, should it not be 6volts as the input is 12volts on mine?

 

[Blood_of_Tyrants]

You'll have some droop when you energize the gp relay. Also, glow plugs don't always have the same resistance.

A fusible link is nothing more than a solid wire typically two sizes smaller (4 number sizes) than the wire it is connected to with a special non-flammable plastic coating. You could also try to get a 40 amp slow blow fuse.

 

[Ken_86gt]

The resistor block will drop the voltage to about 12V only if everything else is working correctly and it is a 24V system. For it to work properly all of the connections have to be good, all of the glow plugs good, relays good, battery connections good, ground connections good.... If you are blowing fuses or links maybe one of the glow plugs is shorted, it usually goes open in a failure, but a short can occur. What is the resistance readings for the individual plugs? I suspect a 40 amp fuse is not enough. From looking at the TM, the link is protecting 8 AWG wire- so the link should be 12 AWG. A 12 AWG link is rated at 160 amps if replacing with a Maxi Fuse (according to one source I found, but it may be too high).

I don't think your conversion was done properly as there is no reason to use the resistor block on a 12V only converted system. If you only have one battery I would bypass the resistor block.

 

[southdave]

10.2 is what is expected, that is from diesel page 6.2 manual

 

[Crash_AF]

The resistor bank is dropping the voltage like it's supposed to, you need to bypass the resistor block by connecting it to the 12V buss. If you are blowing the 40A fuse, you need to replace it with a correct fusible link. A fuse blows too fast during the initial current inrush as the glow plugs warm up.

Later,
Joe

 

[K9Vic]

The resistor bank is dropping the voltage like it's supposed to, you need to bypass the resistor block by connecting it to the 12V buss. If you are blowing the 40A fuse, you need to replace it with a correct fusible link. A fuse blows too fast during the initial current inrush as the glow plugs warm up.

Later,
Joe

Thanks, that makes sense and I just had the 8g wire with a 40amp fuse laying around and did not want to try this with out any fusible protection. I will get a true fusible link cable and see what happens, or a slow blow fuse since the cable is already made.

 

[jdemaris]

.. I have all brand new GP and they are the AC 60G from local parts store.

So my question is, when "wait to start" is on, should all the GP have a true 12volts, or should it be like mine do to the load of them all on at about 5 volts? In this cold of about 30degrees my truck will start, but I have to cycle it at least 4 times to kick.

Thank you in advanced and this site has been a great help!!

AC60Gs (Beru in Delco boxes) work like this, and should be hooked to a 12 volt source capable of at least 70 amps. No resistor. Each plug as thus:

In 5 seconds, each should be 10 volts drawing 8 amps and 1200 degrees F.
In 9 seconds, each should be 10 volts drawing 7 amps and 1560 degrees F.
In 14 seconds, each should be 10 volts drawing 6.7 amps and 1780 degrees F.

 

[jdemaris]

Thanks, that makes sense and I just had the 8g wire with a 40amp fuse laying around and did not want to try this with out any fusible protection. I will get a true fusible link cable and see what happens, or a slow blow fuse since the cable is already made.

8 plugs drawing 8 amps each equals a total of 64 amps draw. A 40 amp fuse is adequate for only one bank of four cylinders, not all eight.

 

[Crash_AF]

Your other option would be to bypass the resistor block with a dedicated wire running from the big buss bars on the passenger's side with a 70A fuse.

Later,
Joe

 

[Ken_86gt]

AC60Gs (Beru in Delco boxes) work like this, and should be hooked to a 12 volt source capable of at least 70 amps. No resistor. Each plug as thus:

In 5 seconds, each should be 10 volts drawing 8 amps and 1200 degrees F.
In 9 seconds, each should be 10 volts drawing 7 amps and 1560 degrees F.
In 14 seconds, each should be 10 volts drawing 6.7 amps and 1780 degrees F.

Interesting info, but there seems to be other sources that say that each plug should be 13-14 amps for AC-60G. This source says that each bank should be drawing 50-55 amps, or 100-110 total. GM Diesel Hummer Glow Plug Operation, Testing & Troubleshooting

 

[doghead]

Why do you want a fuse in the Glow Plug supply wire? It never had it before. There is very little chance there is ever going to be a direct short to ground(without human intervention). It just makes no sense.


Also, I recently posted a link to a chart comparing AC, Bosch And Wellman GP's(time temp, amps/volts) Search!

 

[K9Vic]

Thanks to everyone for all your help.

I bypassed the resistor block after adding a correct fusible link to handle the 110 amps expected with 150amp (I did not want to even test with no fuse for safety). Here in Fort Worth Texas it is 45 outside and before it would take effort to start when it was even warmer out. Now after the fix, my first test the WTS light was on for only about 15 seconds and the truck started right away and no gas peddle depressed. So the place that did the 12v conversion did not do it correctly and this caused hard starting. I went over everything else and the rest looks correct as far as I can tell.

Now when it gets warmer, I need to replace the injectors and then everything will be completed.

 

[K9Vic]

Video from today starting my M1010 in this rare Texas cold after I bypassed the resistor block. It was 24f at about 8am the morning when I stared it with no problems like I had before. It probably would have not started with the resistor still hooked up. Not sure how the city never realized this before, or maybe that is why they sold it, LOL

[media]http://www.youtube.com/watch?v=BXegIX6sGTU[/media]

 

[4bogginchevys]

good vid.....makes me want new glow plugs