Morsel

I swapped in a new voltage reg (recommended by a fellow forum member) due to the needle on my volt gauge bouncing. At idle it will jump up halfway and then back down. It does this about every 4 seconds. The volt reg didn't seem to fix this issue. Not sure what to attack next? Any help on where to go next would be great. below is the reg i ordered from summit with the part number..
AND.. when I bought this rig it didn't have a spare tire under it. I got a wheel and tire yesterday and went to put in in and it looks like it is missing a few things. My owners manual doesn't show how to remove the spare tire so I am not sure what is what under there.
in the pics below is all that was under there.
What am i missing?

NJTman

Couple things to look for regarding the VR.
All grounds need to be clean including, engine, battery, frame, body. Lost of threads regarding 1st gen ground issues. Good to add new grounds, one from alternator to negative battery cable, ad per Jim Lane alternator upgrade.

Diodes in alternator can be going bad as well. Recent threads discussing this very issue.

The tire carrier bolt was cut in your photo. You can substitute a long carriage bolt in its place. It mounts to the driver side frame rail, and the other bolt you have with the hook on the end goes on the passenger side frame rail, with its end through the hole in that long metal channel in the center of your photo. The tire sits above that channel, and holds it up against the under side of the cross rails, between the side rails.
Can't post a photo, as my camera fried up today by a welding spark.

edwinsmith

I have a similar issue but mine is overcharging and putting about 15.5 Volts on to the battery. I don't have a voltmeter in the dash I have an ampmeter which doesn't work.

The overvoltage and fluctuating voltage had to do with the fact that the regulator gets it voltage sense after the battery current passes through the bulkhead connector twice and the ignition switch. When loads are placed on this line and excessive resistance in the connectors and the ignition switch it causes the sense voltage at the regulator to be low and fluctuating. The regulator thinks not enough voltage is getting to the battery so it jacks up the field current in the alternator which puts out more voltage to the battery. I'm not sure where the fluctuations come from.

The solution is to use a relay and run the sense voltage directly through the relay to the regulator. The power previously going to the regulator sense terminal now actuates the relay when the ignition is on. There is a "Sticky" that deals with installing the relay. 89-91 Voltage "pulsing" issue solved! https://www.dieseltruckresource.com/...solved-317745/

I'll be installing the relay this weekend.

Morsel

thanks for the help!
I got under there and cut the long carriage bolt on the driver side. It was bent. I pulled off that bigger bracket. Then up above that was another bracket. I pulled that one as well. Does the spare meet that other bracket above and hold the tire to the body? And once the tire is in there secure do you unscrew the strange screw thing on the passenger side in order to get the tire out? Is that how this setup workds?

thrashingcows

If your voltage is cycling, then perhaps your grid heaters are running all the time?

Morsel

found a decent you tube link on the spare tire setup under these rigs..

samiam4

Does all that go through the the ignition switch?



m

edwinsmith

The grid heaters run off the battery through a couple of relays on the left fender well. They are controlled by a heater controller which is triggered when you turn the key to on. I have heard that the heaters can come on after the engine is running if conditions are right or a temp sensor is bad. It's never happened to me though. I DID have a condition where the Wait To Start light would flash when the truck was running but the grid heaters didn't come on. The air temp sensor was loose causing that.

You could check the heater relays to see if they're coming on with a voltmeter under the hood while the engine is running.

Morsel

my heater blower motor is not working. I wonder if this issue is related

j_martin

T-cows mentioned something you need to check out. It is normal after a cold start for the grid heaters to cycle for some time, depending on the temperature. When intake manifold temperature gets up to spec, it stops. A faulty temp sensor can make the heaters constantly cycle. 4 seconds on and 4 seconds off is about normal.

The heaters draw about 200 amps, overwhelming the 120 amp alternator.
Put a volt meter or test light across the coil contacts on a grid heater relay, or on a heater terminal itelf and see if that's it.

Morsel

after installing the new voltage reg I started it cold having sat all night. It did the 4 second cycle for a few minutes. I then shut it off. Later in the day I came back out and fired it up and drove up to a spot I am cutting wood. The needle didn't bounce or cycle or anything abnormal. So i would suspect that initial cold 4 second cycling is normal.

edwinsmith

If your ignition switch is flaky it could cause the blower motor to not work as well as not providing a good sense voltage to the voltage regulator. Do your power windows work with the key on? The power windows and the A/C Heater blower come off the same section of the ignition switch. SO if both don't work then your ignition switch is likely bad.

The VR sense and other engine controls come off a separate section of the Ignition switch.

The radio and other accessories come off a third section of the Ignition switch and finally the starter is activated by the 4th section of the ignition switch.

Do you have an FSM for your truck? I have one for the 89 D350 and a 92 Ramcharger. If you don't have the FSM with wiring diagrams I can provide you with a link to mine via a Personal Message.

Edwin

Morsel

my rig is bone stock, not intercooled, no AC, no power windows. I had planned on pulling the blower motor and applying 12v to it outside the truck to see if it is working. Are there NEW ignition switches available for these rigs?
Is this the ignition switch>>>???

edwinsmith

That looks like the switch for the tilt wheel. What year is your truck? Mine is an 89 with a non-tilt wheel. On mine the ignition mounts down on the steering column and attaches to the key with a push pull rod. Yes the switches are available.

DO you need the FSM? It has wiring diagrams.

Edwin

Morsel

Mine is a 91 with no tilt wheel and no power windows
Just sent you a PM Edwin thanks