i have an 87 k5 with a 88 k2500 engine. That engine has a cs130 alternator. Recently my alternator hasnt been charging my battery right. If i turn on my radio, high beams, heater, 4 kc lites, and 2 bumper mounted lights, my ammeter drops down to 8 to 9 volts and thats if it doesnt shut off. Just started yesterday and i figured the alternator was going bad. So i replaced the alternator with another cs130 today. Still shutting off when i have a couple lights on and heater etc. its almost like its not charging fast enough to keep up with the load. I was looking at my wiring and into the cs130 i have one brown wire that has been spliced onto the harness from a PO and i have one wire going back to the battery on the side of the alternator. The wire going to battery is about 8 gauge with two splices in it. One splice in it is unusually warm to the touch and has made the plastic connecter on the splice soft from the head. I was going to replace this with 4 gauge wire. But after researching some, the cs130 on my truck will usually have two wires instead of just one brown like i have. Do i need to have two wires coming out of the alternator plug? Is there a wire i need to add in? Or will that one brown wire work after i replace the wire going to the battery?
CK5
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Alternator wiring problem?
- Thread starter Morgan3
- Start date
Sounds like you have gotten some corrosion in that splice and its not making a good connection anymore. When you feel heat in a connection or wire, that is where you are losing power.
As a general rule, its always OK to replace a wire with a heavier wire. EXCEPT in the case of a fuse link. They are deliberately undersized to burn out and break the circuit before a fire starts.
But, what you are describing is not a fuse link, others who work with these trucks daily will chime in and give you more accurate info.
One other thing to check when an alternator stops keeping up with a load, is the fan belt. Make sure its in good shape, tight, and not slipping.
As a general rule, its always OK to replace a wire with a heavier wire. EXCEPT in the case of a fuse link. They are deliberately undersized to burn out and break the circuit before a fire starts.
But, what you are describing is not a fuse link, others who work with these trucks daily will chime in and give you more accurate info.
One other thing to check when an alternator stops keeping up with a load, is the fan belt. Make sure its in good shape, tight, and not slipping.
Sorry shpuld have mentioned i have a serpintine belt set up so it wouldnt be just the fan, even though i believe my fan clutch is also on its way out in the near future. So the one brown would be all the alternator needs to work at that connection? Because that is what confuses me about the wiring.
bp71k5
3/4 ton status
Your battery may be dying or have a dead cell.
My '90 Jimmy has the tan wire and a black wire in the plug. I believe that it needs both to turn on the regulator and give reference voltage.
Not sure which wire is which a.t.m.
Not sure which wire is which a.t.m.
New battery that is only 2 months old. Was planning on testing it tommorow to make sure. Along with manually checkibg volts with a voltmeter on all connections.
I've never really heard an authoritative answer, but on the CS130 trucks (R/V) I've dealt with, all had a "charge" light that is part of the circuit to get the alternator charging. Some report they run the CS-series without anything of the sort, but perhaps under proper conditions, what you are experiencing is the result?
There is an adapter plug made to run the CS-series in place of the older SI-series, and it has a resistor as a component to eliminate the requirement for the bulb in the dash. I don't recall having to splice/cut anything to swap the CS into my truck using the adapter plug. These are the reasons I do not generally like splices...correction...this is the reason I generally don't like PO's.
There is an adapter plug made to run the CS-series in place of the older SI-series, and it has a resistor as a component to eliminate the requirement for the bulb in the dash. I don't recall having to splice/cut anything to swap the CS into my truck using the adapter plug. These are the reasons I do not generally like splices...correction...this is the reason I generally don't like PO's.
Yeah I would have much rather have gotten a bone stock k5, but i decided the next best thing was one with almost completely new drivetrain. I checked volts today at the battery and it was a constant 14v at idle, even after turning everything on, it only dropped to 12 at the lowest. My gauge in the truck is apperently inaccurate because the gauge dropped to 9 or 10. Also truck acted like it was about to cut off. Also replaced the alternator to battery wire with 6 gauge wire i had. Going to clean and replace ground wires on the battery and trace back any wiring that has to do with the battery tomorrow. Hopefully i can fix this problem. Also i have a surging issue that seems to be related to this so hopefully i can knock out both problems.
Try to check the connections which feed power to the cab. Maybe there is somewhere not giving full volts to the ignition switch. But it could possibly be the ignition switch itself. I am just thinking that it seems to be charging, but the gauge shows low volts and engine can die. This leads me to something past the terminal block where the alternator power is tied.
bp71k5
3/4 ton status
If you have 14V at the battery with the engine running, there's nothing wrong with the alternator. Sounds like you might have a bad gauge, or a loose/bad wire on the gauge.
Probably likely that your gauge is somewhat inaccurate, but still indicating something isn't right. You can "read" voltage at the fuse panel, it's about as close to the gauge as you can get without doing a bunch of work pulling the instrument cluster, and you can also check it at the junction block on the firewall, to see if there is any major loss there.
A good idea to check voltage on a few different fuses, both constant and ignition switched. That will help narrow it down. I *think* the fuse handling the instrument panel is labeled as such. In any case, that's where the gauge gets its reading.
IMO the gauges should be used for relative readings...any deviation from what they read normally is something to keep an eye on, but expecting the voltmeter to read 13.5V when the alternator is putting out 13.5V is pretty unlikely. There is a lot of wire between the alternator and the voltage gauge, and the instrument panel wiring connector is notoriously poor at conducting.
A good idea to check voltage on a few different fuses, both constant and ignition switched. That will help narrow it down. I *think* the fuse handling the instrument panel is labeled as such. In any case, that's where the gauge gets its reading.
IMO the gauges should be used for relative readings...any deviation from what they read normally is something to keep an eye on, but expecting the voltmeter to read 13.5V when the alternator is putting out 13.5V is pretty unlikely. There is a lot of wire between the alternator and the voltage gauge, and the instrument panel wiring connector is notoriously poor at conducting.
Had my buddy take a look at it with me today. Hes a lot better at electrical than i am. He found that the coil was getting 9 volts at times. Traced it back to the ignition switch which was also getting 9 volts. Going to change the switch out with one that was in my parts truck sometime this week. I didnt get a chance to clean my ground connections like i planned because of rain. Will post back here with results after changing the ignition switch and cleaning ground wires.
Glad that you found something!
So you had good voltage into the switch, just not coming out of it?
Had that happen before....
So you had good voltage into the switch, just not coming out of it?
Had that happen before....
I tried a new ignition switch last week but the ignition switch didnt seem to have enough room for adjustment in it. I could only get the truck to turn off with the key and manually turn on by moving the rod, and same the other way. Could only get it to turn on with the key, and off manually by moving the rod. But while i had it in, my voltage was still dropping down to 9 volts but not as often as before. Had to take out the new ignition switch anyways and get a different one. Went to oriellys and got a BWD ignition switch. During all this, i noticed that my dimmer switch was going out because the wire that has a constant 12 volts was unusually hot to the touch and my bright lights were always on. Decided to also get a dimmer switch.
Wednesday night i replaced the whole distributor and coil. Reason i did this is because on identafix, someone else fixed their problem by doing this. Truck ran amazing, got rid of my surging, but voltage was still dropping, not as bad but not good enough for me. Cut off on me at a red light once between that night and the next day.
Today i put in the new dimmer switch and ignition switch. Adjusted everything, cranked it up, no more voltage loss. Cant get it to drop below 13 volts (according to the ammeter in the dash) with heater, high beams, hazards, radio. So hopefully the problem is fixed.
Sounds like you are overloading the alternators job. You need to figure out the amp draw on ALL devices you want to run at the same time then make sure you have an alternator that is slightly greater than the amp rating you need.
