1984 Toyota Sunrader, Issues With Power

[PatrickFisherProject]

I have a 1984 Toyota Sunrader.

About a month ago I started to notice a few oddities occurring.

Oddity 1: When I turned my turn signal on my seat belt and brake lights would flash in succession with my turn signal.

Oddity 2: When I switch my low beam to high beam my lights would cut out. If I did it a second time my high beam would stay on.

This week two more detrimental oddities began occurring.

New oddity 1: When I turned my lights on after start my car it would kill all power in my vehicle.

New oddity 2: If I slowed down (whether coasting or braking) I would lose all power in my vehicle.

The first time this occurred I tried to use a battery bank to jump start my vehicle. It received an error code and wouldn't jump start the battery. I wiggled the terminal cables and was able to start my car back up. I thought my terminals may be loose so I tightened everything.

This didn't completely resolve the problem. I took the vehicle to Firestone, the only garage open on Sunday. They tested the batteries and both passed. They also didn't find any issues when diagnosing my electrical system. The only thing they did was tighten my main battery in place.

Any thoughts as to what may be causing this problem? My initial thought may be the ground. I noticed the ground from the wire is connected to the truck body, and not the frame. The body is painted and there is 31+ years of grime. I thought that maybe I should clean the area and grind away all traces of paint.

Any insight would be appreciated.

[zero]

Without even thinking hard about it - you for sure have a bad common/chassis/battery-NEG AKA "ground" issue. There is supposed to be a substantial sized cable - like a #2 or #4 AWG - going directly from the battery negative post to the engine. It attaches to the engine often at the starter motor or to the intake manifold. All I see hooked to your NEG post is a heavy lead going to the fender sheet-metal. Toyota never used any heavy leads to ground the sheet metal (not that it would hurt anything). But now - when the alternator - or headlights - or starter-motor needs power - where is NEG supposed to come from? Is there another heavy lead somewhere bonding the sheet-metal to the truck frame and engine? OEM Toyota uses a heavy cable from NEG post to the engine mass. Then a few small cables attaching the engine to the sheet metal and battery NEG to the sheet metal. Also a small gauge jumper wire or two bonding two sides of rubber isolators (like on engine mounts or trans mounts). Can't recall if my Toyota has them or not.

[PatrickFisherProject]

Without even thinking hard about it - you for sure have a bad common/chassis/battery-NEG AKA "ground" issue. There is supposed to be a substantial sized cable - like a #2 or #4 AWG - going directly from the battery negative post to the engine. It attaches to the engine often at the starter motor or to the intake manifold. All I see hooked to your NEG post is a heavy lead going to the fender sheet-metal. Toyota never used any heavy leads to ground the sheet metal (not that it would hurt anything). But now - when the alternator - or headlights - or starter-motor needs power - where is NEG supposed to come from? Is there another heavy lead somewhere bonding the sheet-metal to the truck frame and engine? OEM Toyota uses a heavy cable from NEG post to the engine mass. Then a few small cables attaching the engine to the sheet metal and battery NEG to the sheet metal. Also a small gauge jumper wire or two bonding two sides of rubber isolators (like on engine mounts or trans mounts). Can't recall if my Toyota has them or not.

There are two batteries in the Sunrader.

The main battery has the NEG connected to the sheet metal. The POS runs across the vehicle into the isolator along the right side.

The auxiliary battery has the NEG connected to the metal along the radiator. The POS runs back to the isolator along the right side.

The isolator has a NEG wire that runs down to the alternator.

I don't see any NEG wires running from the sheet metal to the engine.

[payaso del mar]

I think he's right; this stuff all sounds like iffy ground issues. sometimes you'll also see gauge issues, such as temp gauge being affected by turning on the headlights.

the good news is that aux ground wires are cheap and easy to add. you cannot have too much grounding. try adding another body ground and a jumper to the engine and see what that does. you can get welding cable from #6 to 2/0 and heavy copper terminals at Ace Hardware for reasonable price.

[zero]

The main battery has the NEG connected to the sheet metal. The POS runs across the vehicle into the isolator along the right side.

The auxiliary battery has the NEG connected to the metal along the radiator. The POS runs back to the isolator along the right side.

The isolator has a NEG wire that runs down to the alternator.

I don't see any NEG wires running from the sheet metal to the engine.

The way the aux battery is hooked up is fine and has nothing to do with the other issues. The 12 volts DC system that the camper-coach uses rely on the truck frame as a common connector for NEG power from the aux battery.

The "main" battery MUST have at least one heavy-gauge wire hooked directly from the NEG post on the main battery to either a large bolt on the starter-motor or the engine block somewhere (often the intake manifold).

In addition there has to be at least one, and hopefully two small-gauge cables connecting the body sheet-metal to the engine.

The isolator NEVER has any NEG wires hooked to it so you've got me a little stumped with your comment. You appear to have a NOCO 90 amp isolator made for three-terminal or four-terminal operation. A 1984 calls for the three-terminal hookup assuming your alternator uses a separate external voltage-regulator. So one post goes to POS on the house battery. Another post goes to POS on the main battery. Another post goes to the output terminal on the alternator. The fourth "E" post gets hooked to nothing. On a later truck - it would have to be used.

On the subject of the symptoms you mentioned. All can be a ground issue except the headlight problem. But maybe something is lost in translation here. The headlights - low or high beam work off of one single relay. So if a low beam works and a high beam does not -it has to be a problem with the dimmer-switch or wiring beyond it. Now if all the lights stopped working - it is back to a ground issue.

[Maineah]

Multiple issues you need to address them one at a time they are not all related.

[PatrickFisherProject]

The way the aux battery is hooked up is fine and has nothing to do with the other issues. The 12 volts DC system that the camper-coach uses rely on the truck frame as a common connector for NEG power from the aux battery.

The "main" battery MUST have at least one heavy-gauge wire hooked directly from the NEG post on the main battery to either a large bolt on the starter-motor or the engine block somewhere (often the intake manifold).

In addition there has to be at least one, and hopefully two small-gauge cables connecting the body sheet-metal to the engine.

The isolator NEVER has any NEG wires hooked to it so you've got me a little stumped with your comment. You appear to have a NOCO 90 amp isolator made for three-terminal or four-terminal operation. A 1984 calls for the three-terminal hookup assuming your alternator uses a separate external voltage-regulator. So one post goes to POS on the house battery. Another post goes to POS on the main battery. Another post goes to the output terminal on the alternator. The fourth "E" post gets hooked to nothing. On a later truck - it would have to be used.

On the subject of the symptoms you mentioned. All can be a ground issue except the headlight problem. But maybe something is lost in translation here. The headlights - low or high beam work off of one single relay. So if a low beam works and a high beam does not -it has to be a problem with the dimmer-switch or wiring beyond it. Now if all the lights stopped working - it is back to a ground issue.

I appreciate your insight and help.

I was reading about symptoms of a bad ignition switch online. It sounds like some of the symptoms displayed could be a result of a bad ignition switch. Any thoughts?

[zero]

I was reading about symptoms of a bad ignition switch online. It sounds like some of the symptoms displayed could be a result of a bad ignition switch. Any thoughts?

Some things it is possible and some things it is not possible.

You cited four issues:

"Oddity 1: When I turned my turn signal on my seat belt and brake lights would flash in succession with my turn signal"

The turn signal and the warning light are tied together in the same positive circuit. The light is activated by getting a NEG signal and it likely getting a weak one by backfeeding through the turn-signal circuit due to a poor NEG connect to the engine or chassis or sheetmetal.

"Oddity 2: When I switch my low beam to high beam my lights would cut out. If I did it a second time my high beam would stay on. "

The high-beams draw more power then the low-beams. So it is possible that with a bad NEG battery connection truck - low-beam might work but once the extra amp draw is need for the high-beams the bad connection gets hot and stops working all together. But that does not explain it working when you hit the dimmer switch a second time. Good reason to blame the dimmer switch. Easy way to tell for sure is this. When the headlights do not work again - check NEG and POS power at one of them and see which is missing. The headlights work like this. At least as far as I can tell. The print is so small in the factory wiring diagram I can barely read it even though it is a five-page pull-out section just for the lights. Positive power for the headlights come from the headlight relay and headlight switch. Negative power comes from the dimmer switch. Note that the Positive power does NOT run through the ignition switch. It runs directly to the battery POS with two fusible links protecting the circuit (one time blow fuses).

.

"Oddity 3: When I turned my lights on after start my car it would kill all power in my vehicle."

That is a classic sign of a bad NEG connection to the frame, engine, or sheet-metal somewhere. When you first turn something on - it works up to a certain level of amp flow. Then when flow gets too high for a bad connection - it overheats and then all connection is lost. Very common in American cars built in the 70s-90s. Very UNCOMMON in Japanese vehicles because of all the extra NEG leads they use. YOURs are missing.

"Oddity 4: If I slowed down (whether coasting or braking) I would lose all power in my vehicle."

It is likely - due to to a poor NEG battery bond to frame, engine, and/or chassis - you are running just off the alternator and at low speed - it craps out.

[5Toyota]

the stock Toyota starting battery ground cable on my rig has 2 leads a very short one to the fender well and a long one to the engine block. I see no ground cable from starting battery to motor block in your photo. Both my dolphin and 4wd have ext same set up.