Gen 1 driver side not charging right

[acesneights1]

Truck has the stock unmolested dual alt system
It will only charge if the engine is revved way up then it will stay excited. If the truck is shut off it will not charge until that is done. I had the alt tested and it is fine. The gen 1 light does not go on with the key. Bulb is good. I have no keyed power going to the 2 wire plug but even stabbing that wire with a test light is enough to cause it to excite and charge(sometimes). Fuses under dash are all good. what am I missing ?

 

[aebiv]

What is way up? It takes about 1100RPM for mine to kick in, which I believe is quite normal.

As for the rest of it?

Weird

 

[Westech]

what do you mean reved way up? most if not all cucv's need to be idled up a bit to get both alts to charge, but not 3500 rpm.. more like 1k or so.

 

[papercu]

First thing I would do is swap the alternators and see if the problem stays with the alternator or at the position? Wayne

 

[acesneights1]

Alternator was bench tested at a local auot elect shop. It's good. Yes more than 1100. I would say atleast 2000 maybe more. It's not getting keyed power to excite it. There is a two wire plug that snaps into it and the Alt shop told me one side should have constant power and the other should be keyed power Is that correct ? If it is then the keyed power is not getting any. I traced the wire back to the plug where it goes into the firewall and still had no power there either. So the problem has to be under the dash/inside the truck but where ? Could the circut board on the instrument panel be the culprit ? It's a PIA to get out but I will if needed or is Gen 1 looped through the Voltage guage that is not factory ? Somewhere in the truck there must be a problem but not sure where to look. I have the TM but I'm not real good at reading schematics. It's a little confusing. Basically is the volt gauge in the same loop with gen1 ? Is the fact that the light doesnt come on wih the key an indicator of my issue ?

 

[davo727]

If you pull the dash pad out and unbolt the cluster and pop the speedo cable off the cluster it will give you some good access to inspect that stuff

 

[ehuppert]

Went through this with my 08, but seeing as how converted to SBC alt isn't the same. On the older alts power to light (excite) is "pwered" by ign, then grounded through regulator unit. In my case it was a bad alternator that wasn't grounding the circuit.

You can reach up from below with test light (difficult, but possible) to check for power at the printed circuit by the bulb. For that matter, you can disconnect alt plug and see if power is coming from dash to excite circuit. you can also check terminal in alt to see if powered with veh off. If so, most likely regulator. Of course this is assuming that the mil alternator works on the same priniciple as the 10 si. (sure someone will correct me if i'm mistaken?)

eric

 

[Warthog]

The Gen 1 and Gen 2 dash lights are required for the charging system to work. They are part of the circuit design. No Bulb, No worky.

The Gen 1 bulb gets it power from the ignition switch. It is supplied thru pin #5 on the instrument cluster circuit board. Pin #5 supplies power to Gen1, 4x4 light and Oil light. It is 12v.

The circuit goes thru the Gen1 bulb and out Pin #2, passes thru a brown wire, thru a harness connector and continues to Plug #1 on the drivers side alternator.

Plug #2 is hot at all times and is the red wire. It is connected to the 12v terminal on the firewall next to the Glowplug Relay.

First thing I would do is disconnect the batteries and remove and clean all the fuses and fuse holders at the fuse box. A can of electrical contact cleaner and a piece of sand paper or small file is required. They are known to collect dirt and grime thru out their 25+ years of service. With clean fuses, we can check more items. I have seen many issues corrected with just cleaning the fuses

If that doesn't help, then remove the instrument cluster and clean all the bulb sockets and copper contacts on the circuit board. These are also known to corrode over they years. Use a piece of steel wool to clean the contacts on the circuit board. While you have the cluster out you can use an ohm meter and check all the circuit paths to make sure the connections are good.

I have included some pics of the instrument cluster and the Gen1 circuit. I colored the Ignition circuit in purple.

Here are some links on how I fixed my instrument cluster.
http://www.steelsoldiers.com/electrical/43351-cucv-instrument-cluster-repair.html

http://www.steelsoldiers.com/cucv/46054-cucv-instrument-cluster-decoded.html

Check these items and let us know what happens.

Warthog

Right click on thumbnail and choose "Open Link in New Window" then save the file and you can open it and zoom in if needed.

 

[Grantshire]

First thing I would do is swap the alternators and see if the problem stays with the alternator or at the position? Wayne

I have (I think) the same problem on my daughter's M1009 and have made her park it until I get this figured out (she is not happy about that!). Are these two alternators the same? If so, swapping them would tell me if one is bad because I don't really trust the local idiots to test one. The Gen 1 light stays on and her gauge show charging is not what it should be.

 

[Warthog]

If the truck is stock, then the two alternators should be the same.

They are regular 12v alternators, EXCEPT the the ground for the internal electronics is conected to the gound post and NOT the case.

Any shop should be able to check them. They just have to attach the ground wire to the post and not the case.


You can have a good shop rebuild them for less than $100 ea.

Or you can rebuild it yourself.
http://www.springhillautoelectric.co...d&productId=13
Includes everything except a new ground terminal


If you want new, ebay has them or you can go to NAPA. for a rebuilt one. I posted the Wilson/Napa part number in the CUCV Wiki page Cost about $220 each

If you truck is still 24v, make sure you get the alternator with the Isolated Ground. There was a recent post explaining the Isolated Ground



Right click on thumbnail and choose "Open Link in New Window"

 

[dstang97]

I had a to clean everything to fix mine the contacts on the bulb cluster and main harness. Try turning the light a couple of times before taking everything apart to get a good contact.

Grantshire check both batteries with a multi meter before swaping them. They should both be 14v ruining

 

[acesneights1]

So I finally figured out what was wrong with it. Picture worth 1,000 words...

 

[Warthog]

That would make thing not work. Glad you found it.

 

[acesneights1]

I soldered a wire directly to the bulb and then scotch loked it to the corresponding wire in the harness as a quick fix. The local Junky has an M1008 so Tues I will stop by and see if the cluster is good. The whole ribbon on mine looks hurtin.