convert M1010 electical to 12V details

[swyne]

I have found the conversion for the other trucks. Is there a detailed conversion for the M1010? Like what to do with the Blue Box (which is new) and details on how to do rewire the bus bars. I had both alts done over, two new Dekas. I had replaced the heater core last night and while it was running the front battery was dropping. I had the heater on high. When it reach 11.5V I shut it down. I was checking for leaks and warming the engine to see how well the heater worked when I decided to measure the batteries. After turning the truck off I checked everything removed all my tools. Got back in to move out of the shop. The starter wouldn't work it made an engaging sound and thats it. I turned the key back and tried it again and the the starter stuck on!! After hurrying to remove the a battery cable It had melted the blue section of wire on fire wall to a powder that comes from the rear battery (red/blue) then to the small little junction block near the brake system on fire wall. I would love to keep the truck original. ('87 m1028 w/ambulance pkg) but I really want to rely on the truck and know it will start with no funny business under the hood with this type of system that seems to be plagued with problems. I know the alts were in perfect shape once completely rebuilt. I hope the system didn't damage them. running they should of been reading (from the battery) more that 11.5V on the front and less than 15.7V on the rear. SO it sounds to me that its a screwy set up from the begining. So going to a 12V system seems to be in order. Thank you for any help on this dead horse of a topic. I forgot to mention I checked the 12V relay under the dash. Its fine. So possibly the 24V relay in the starter?. This is what led me to having to make a decsion. Buy a 24V starter or move on to 12V.

 

[swyne]

Heres a couple pics

 

[colomil]

I have a M1010 that was butchered by DRMO, to include stealing the "blue box". I considered converting to 12v but I believe the rear A/C uses 24v for the fan. I thought about putting M1009 alternators/brackets on so I could keep the 24v and ditch the regulator. Look up the M1010 wiring diagrams on tpub.com, there is enough info to figure our how to convert to M1009 24v or 12v.

 

[CCATLETT1984]

I would do as colomil did, get the alternator setup from a m1009 or m1008 and put it on your truck so you keep the 24v, plus you will still be able to use the TM's for wire troubleshooting.

If you were to change over to 12v, you'd have to find a 12v alt. that would bolt in place of the stock one, the blue box would be removed since the replacement alternator would be internally regulated.

we have the TM's here on the site, although they are kinda hard to get to right now (will change soon.)

At the top of the page, click on resources, then "tech manuals" go through the pages until you see the ones marked CUCV, and download them.
To download them, right click on each and click "save target as".

 

[mangus580]

Is the only reason you want to switch, because your starter is dead????

Go to ODiron, and buy a new starter... and be happy with it.

 

[devilman96]

Yeah I strongly recommend that you DON'T convert the truck to 12V... You get into the "one off" category and will have zero help when you need it.

Problems are to be expected with a 20 something year old truck. I would say 75% of the electrical issues with CUCV's are OWNER INFLICTED problems. It always seems the last thing anyone wants to do when turning a wrench is pick up a manual and READ FIRST... It's always after they fry something!

As Mangus said... Get a gear reducted starter... Doesn't matter if you buy it from me or anyone else. Lower amperage with much more speed and torque, plus they don't fall apart!!! (change the starter bolts when installing!!!!) It will be the last starter issue you have!!!!

 

[swyne]

Yeah I agree. I would like to keep the truck all original. I would be happy with replacing the starter as Devilman96 mentioned. BTW what do ya get for a 24V starter? Do you sell the bolts too? I can always throw a new starter in and replaced the the one wire that had melted and then tackle the charging issues. I thought I had it when I replaced and rebuilt everything.

 

[swyne]

I had removed each voltage regulator from the altenators. They are set differently. see pics. where should the settings be at. The bottom one is the high one (all the way to the left) and the top alt is in the middle. (straight up and down). This does have the red wire to the rear and the orange to the front on the driver side blue box. Before i put it back together I would like to hear from someone that knows. the regulators are Transpo 95300s 28V 3396 While running the bottom alt was 15.7 at the bat and the top alt was dropping when the heater was on but was low 12's going into the 11's. See what I don't understand is does the voltage regulator on the fender halt the juice coming from the top alt until it reaches a certain point then sends the juice to the front battery allowing it to charge? Why would my rear battery be so high and front so low? l

 

[devilman96]

gear reducted starter...

Click the link... No bolts... Easily found at Napa, Advanced, etc... I suggest using locktite (blue) as well.

 

[kennyw]

Yeah I strongly recommend that you DON'T convert the truck to 12V... You get into the "one off" category and will have zero help when you need it.

One off like the 2 million other "civi" trucks out there? They all run 12V and are the basis of the 24V system on the CUCV's.

 

[swyne]

OK!! I grabbed my copy of the TB 43-0001-39-8 M1010 retrofit. went through it and just wanted to make sure it was done as described. One thing out of it that I noticed was the potentiometer was NOT turned all the way CCW. I then moved to the regulators on each altenator and adjusted those with a little bit of game playing of making an adjustment and then starting the truck back up to see where it put me, then mabe having to go back and turn a little more etc. I think know I might be ok. I had replace the burnt out wire with another cable set that I had.
Does any one know if the blue section is desinged to melt out like it did. See photos.
I also snapped shots of the voltmeter as the vehicle was running. I had thrown the lights on and heater to draw some power and the front battery was still over 13V. As I increased rpm's both alts increased about .5 to a volt The rear battery was reading 13.8V. I believe 15.7 was a bit high (at idle). I will place a watch on the batts now and where they end up after sitting a week or so. I also took measurements from the DUVAC and it was reading like it should. Off the 12V wire was 13V+ and the 24v side was 27V+.

 

[mangus580]

One off like the 2 million other "civi" trucks out there? They all run 12V and are the basis of the 24V system on the CUCV's.

No, the civvy 12v trucks dont have a 'hacked up' 24v truck as their basis.

The point behind devilman's comment is...

if you convert your CUCV to 12v, we have no clue what was done, and what the wiring looks like. VERY hard to troubleshoot.

 

[mangus580]

OK!! I grabbed my copy of the TB 43-0001-39-8 M1010 retrofit. went through it and just wanted to make sure it was done as described. One thing out of it that I noticed was the potentiometer was NOT turned all the way CCW. I then moved to the regulators on each altenator and adjusted those with a little bit of game playing of making an adjustment and then starting the truck back up to see where it put me, then mabe having to go back and turn a little more etc. I think know I might be ok. I had replace the burnt out wire with another cable set that I had.
Does any one know if the blue section is desinged to melt out like it did. See photos.
I also snapped shots of the voltmeter as the vehicle was running. I had thrown the lights on and heater to draw some power and the front battery was still over 13V. As I increased rpm's both alts increased about .5 to a volt The rear battery was reading 13.8V. I believe 15.7 was a bit high (at idle). I will place a watch on the batts now and where they end up after sitting a week or so. I also took measurements from the DUVAC and it was reading like it should. Off the 12V wire was 13V+ and the 24v side was 27V+.

sounds like the TM helped?

Glad its working for you.

 

[CCATLETT1984]

Does any one know if the blue section is desinged to melt out like it did. See photos.

That is a fusible link, it melted to save the rest of your wiring

I would put a new fusible link on, dont just use a piece of wire.

 

[swyne]

Where can one buy one of these fusible links? or can I wire in a fuse holder for what rated amps.

 

[CCATLETT1984]

fusible links are available at napa, and most good auto parts stores.

 

[swyne]

I have a fuse holder 8ga wire. but I don't know what size fuse to place in it? 15a 20a 30a?

 

[kennyw]

No, the civvy 12v trucks dont have a 'hacked up' 24v truck as their basis.

The point behind devilman's comment is...

if you convert your CUCV to 12v, we have no clue what was done, and what the wiring looks like. VERY hard to troubleshoot.

However, if you do it properly it will be identical to a 12V civi diesel like my '83. That is what 90% of the wiring on the CUCV came from. The 24V system on the CUCV is nothing more than the civi setup with extra's added on to accommodate the 24V system. To convert it your mainly removing the extra's. Nothing complicated about either system.

 

[mangus580]

However, if you do it properly it will be identical to a 12V civi diesel like my '83. That is what 90% of the wiring on the CUCV came from. The 24V system on the CUCV is nothing more than the civi setup with extra's added on to accommodate the 24V system. To convert it your mainly removing the extra's. Nothing complicated about either system.

That is not true. Look a the schematics... there is a lot different. It is not just an 'add-on'. The gauge panel is wired different, under the hood is all different. The glow plug wiring is different, even the headlight system is wired different.

 

[kennyw]

It uses the same diesel fuel gauge, idiot lights, headlight switch, wiper switch, wiper motor, ignition switch, neutral safety switch, and much more... then they add on extra wiring to accommodate the second alt. idiot light and a few other things under the hood. Looking at the wiring from an engineering standpoint it is 90% identical. Even 90% of the electrical connectors are the same. I would bet that a large portion of the wiring colors are even identical.

No they are not exactly the same systems, but they are very much alike and use most of the same parts. GM wasn't going to redesign the whole truck when they won the contract as the lowest bidder. They started with the 12V civilian model and modified it. Most of the truck runs on 12V still. The headlight harness is a civilian harness with an add on for blackout lights.

Converting to 12V or staying 24V is a personal choice, but telling people not to do that because it will make your rig one of a kind and impossible to trouble shoot isn't accurate either. The same trouble shooting principles that apply to a 12V civi truck cover 90% of the CUCV and were the basis for the TM's when GM put them together.