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At first my fuse for my regulator would blow every now and then. Now it blows as soon as you turn the motor over. Plus this kills the power to my fuel pump as well. I traced the wires. I have one wire from the fuse box that goes to the regulator (color white). The 2nd wire is black with a yellow stripe. This wire goes up by the firewall and has a 4 way split. The first wire goes to a relay on the pasanger side (behind a metal cover). Then the next 2 wires go to the idle sensor (near the gas pedal). One goes into the main plug on the front and the other goes into the side of the sensor. I haven't traced the 4th wire yet.

If I don't find any obvious breaks in the wire, would be the next thing to check? Can a auto supply test my regulator?

Correction to make. it was not "idle sensor", but Engine Speed Sensor.

The 4th wires goes up to the instrument panel and goes to the Gen light.
Ever since I bought the truck the gen light has been on.

I dont see any obvious wires that are bad. What next?

Not sure if this is any help, but it did help me sort out which circuit was supposed to be doing what. This is from the Series 10 manual (1980).

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

This looks like a match to the one in my '78, but there is a round plug type also. I think these go for about $40 on RockAuto, locally I found one for $45...

http://cgi.ebay.com/ebaymotors/1975-80-Chevy-Luv-L4-1-8L-1817Cid-Voltage-Regulator_W0QQitemZ150145178722QQcmdZViewItem?hash=item150145178722

Check the ignition switch too, this seems to be a pretty common 'issue' with these trucks. Looks to me like a Datsun 620, or an early 70's Chevy (dash mounted) ignition switch would work.

Here is a link to the Series 5 drawings here on the site, very useful for zooming in:
http://www.luvtruck.com/PDF/Series5.pdf

Do you have a Chevy manual or are you using a Chiltons/Haynes? I can make scans from the Series 10 manual if you need them.

From another post on the fuel pump:



The fuse will pop if the current across it is too much for the rating, or if it's shorting to ground. Isolating the circuits one by one will help to determine where the short is. An ohm meter is the easiest way to check it, I lifted both the pos and neg at the battery and connected my meter to the frame and just started ohming out the various circuits. Good luck.

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

Actually I have a fuse cover, that tells me what each fuse is. I think they are all 15 Amps. I have actually both Haynes and Clymer but not the shop series 10 manuel.

Can a Auto supply test my Regulator? What do I check on the ignition switch? Do they have aftermarket if I need to get one of those?

Thanks!

The fuse cover tells you what it's for, but not where it goes.

The diagram I posted was intended to show the wire colors; which, if your harness hasn't been too badly hacked, can help to find out where the wire actually is somewhere else in the truck. Does that make any sense? For instance, the blue (L) wire has specific connections in the wiring diagram, but the wire may have been tapped, or cut and spliced at various points. Knowing where it's supposed to go and where it actually goes can be pretty entertaining. My truck had two ground wires providing 'power' to the radio. Um no...it didn't work.

I'm not sure who/how a voltage regulator would be checked by a shop, unless it was an electic motor rebuild place. I think with these older pole and winding type regulators, current can become a real big question mark. The fuse I pulled out of my voltage regulator position, after it popped for the the 3rd time, was quite hot to the touch. Electricity likes to morph into heat when it's not happy with the circuit. That's why the fuse is there.

Aftermarket ignition switches are available, I think Autozone has a suitable replacement for about $45.

We seem to have pretty much an identical problem, but I'm not sure my GEN light has ever come on.

Are we having fun yet?

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

Yea, it is a handy diagram. Too bad I traced out the wires before getting it. Doh!. White to the Regulator and Black (yellow stripe) to coil and fuel pump. Like I mentiond before it seems the Black wire seems to have a stock 4-way split. I think you are right that the problem may be with the regulator or the igntion switch.

How would I go about testing the switch? Can I pull it and then use a meter on the contacts?

You should be able to test the switch pretty easily using this:



Put the key in and move it to each position, checking for continuity according to the dots. The terminals are numbered on the switch (I think) and the top part of this image shows which color goes to which terminal post. The two together make it pretty easy to Ohm out the switch contacts.

I used the series 5 pdf file to trace out most of my wiring, it's not identical at the fusebox (mine's a '78 ), but it's much easier to work with. Seems I'm not the only one who has a hard time reading/tracing those tiny lines in the manual. A lot of automotive electrical shops can provide drawings for a nominal cost. The cool thing about that approach is you pay maybe $6 for a set of drawings, and then you can go to Kinkos and make 20 copies. I'm thinking of just taking my manual down and doing 300% copies of it in sections. What I like about this is that you can use markers on the copies to trace out where the wiring is landed. If you screw up (and it's easy to mistrace) just toss it, and start over.

The capacitor for the VR is for alternator noise suppression in the radio circuit. If you use spark plugs in the truck with an 'R' designator you don't really need to worry about it. The 'R' designates that the plug is a resistor type and the noise the capacitor was designed to absorb never really makes it past the spark plug. These trucks were designed in the 70's when a resistor plug was not the standard, today it's the norm. If you are running a massive sound system you'd be doing other upgrades to support the current draw anyway, and you'd probably have much more sophisticated noise suppression.

I finally ordered another VR for my truck, but before I put it in I'm going to clean up all the grounds.

Oh, another thing ... have you replaced the primary battery cables? I did, to clean up the corroded mess that was in there, and now I'm thinking I might have replaced them with too small of cables. Didn't occur to me until the other night as I was backtracking over the 'improvements' that I've made to the truck. As simple as it sounds, this could be a big issue if the current draw is too high for the cable rating. I think I put in #4 cables, but I looked at the stock one again and I'm guessing it's #2 or maybe even #0. You probably already know, the smaller the #, the bigger the wire gauge. Most of the stock wiring in the truck is #12/#14, I think...

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

My primary batters cables are about 4 years old. I don't use the truck that much, but I have cleaned where the cables go on battery posts, the starter, and the ground. I am thinking it may be the battery itself. I periodcally put it on a trickle charger, because I dont drive it that much. After I took the charger off, the motor turned over like twice then started. Usually it takes just a little bit longer to start.
I'll still need to test the switch with a meter.

I'm showing you a couple of pics behind the intsrument panel. I still want to know where the BY wire goes, either the temp or gen light. I am wondering if I have the following wires hooked up in reverse?

On the fuel guage side, theres a yellow wire (the 2nd yellow & green are for the 4x4 light):


Then on the temp guage side, I have the BY wire, (I put a piece of masking tape on it)

Sorry for the slow response Zane.

OK, I spent a couple of hours looking over the Series 10 wiring diagram, and here's what I've found:

Black - (The black wire you spoke of with 4 taps on it) Ground

This is pretty normal DC wiring, Red or Black/Red for + and solid Black for -. It's easy to check, just put one lead of your voltmeter on the negative terminal of the battery and ohm it out to your black wire(s).

Gauge Cluster:

Yellow & Green - 4x4 indicator lamp/switch

Now here's where it starts to get fun. I believe the other wire in your photo is not just yellow. According to the diagram there is a Yellow/White wire landed on the cluster also. This goes directly to the oil pressure sender. Another easy one to OHM out. Just pull both 'yellow' wires off, attach one lead of the voltmeter to the Oil Pressure lead under the hood, and see which one ohm's out at the cluster. The Yellow/White wire should go to your Oil Pressure lamp in the cluster. The other one should be the Yellow one, which goes back on the 4x4 lamp. The Green (Light Green in the diagram) goes to one side of the actual 4x4 switch and the other side of the 4x4 lamp in the dash. From your photo, it looks like it would be possible to have the YW and the Y switched. This is bad news if your 4x4 lamp is on all the time, it means your Oil Pressure lamp is the one that should actually be lit...

Now for the Black/Yellow, you really kicked my butt on this one...hahaha...

Black/Yellow at the gauge cluster - 12V source w/ignition in ON (and RUN) position.

-Heat Warning Buzzer
-Thermo Controller
-Fuse box output side (2nd fuse from the firewall)
-Resistor bypass Relay (under cover on pass fenderwell)
-Fuel Pump Relay (under cover on pass fenderwell)
-Ballast Resistor (+ side of coil)

Each of the harness side plugs listed above should have a BY wire on them. I have no idea, physically, where the first two components are located. It looks like they may have something to do with the catalytic converter? Some of the other guys can chime in here.

Not sure if you have a California truck, but these breakouts did not show any dotted lines on these circuits for additional CA emissions stuff.

Finally, you've probably already done this, but if you are wringing out the wiring by yourself a great little helper is a 10' long piece of speaker wire with an alligator clip on each end. This lets you do lots of cool things, you can put a crimp on spade in one of the clips, slide it into the harness plug up under the hood, and then clip the other end to one of your meter leads. Then it's just a matter of using the other lead on the wires under the dash. Also, you can clip the 'gator onto your battery ground post to ohm out the black wire (ground) circuit inside the cab. I've used this for years, there is nothing more frustrating than cranking yourself under the dash just to find the other end of your meter fell off/out of the place you thought you had it wedged...grrrrr.

Anyone out there with better wiring T-shooting skills, please let me know if I've misdiagnosed anything here.

Hope this helps

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

Wow youdid a lot of research! Its not the 4x4 light that is lit. The BY yellow has power to it, so it lights up whatever I have it hooked up to. In this case its the Heat light. I dont think I have a heat buzzer, or if I do it doesnt work! lol.
I think you are right about the catalytic converter. It has something along the lines of a O2 censor that screws in the side of Cat. At least it doesn't hurt the funcnatility of my truck.