2006 Voltage Gauges Batt Fuse and AC Cycling

Thank you everyone who contributes to this forum. It truly saves so much of us time and money by providing knowledge. Here is one that has me stumped.

Voltage gauge was fluctuating down to below 12V and "battery" light flickering on. This started occurring suddenly. Had battery checked next day at auto-parts store, was told it was bad and, since it was 7 years old I decided to replace it.

Voltage low for approximately 30-40 miles but so was idling and I'm sure it was because of the computer re-learning.

Everything seemed fine for a few days and then I started getting the fluctuating in voltage again. This time, the battery indicator never turned on nor did the fluctuations drop below 12V.

Changed out the alternator, tension pulley (not the tensioner itself as it felt fine) and serpentine belt. Again 30-40 miles of "re-learning" with low RPMs less than ideal voltage at gauge. Once again everything fine for about a week after these repairs. It was after about one week that I noticed that the drops in voltage at the gauge occurred whenever the AC compressor cycled on and that the compressor was cycling on for about 10-30 seconds and then off for 5-10 seconds. I wish I remembered if I had been using the AC or heater when the issue first became noticeable and right after replacing the alternator.

I decided to stop using the AC due to limited time to continue to attempt repairs. About a week and a half after replacing the alternator, I had no power to the dash gauges or ignition but all other things (windows, lights, seat heaters etc) had sufficient power. Voltage at battery with multimeter was excellent. I found that the "batt charge" 30A fuse was blown out. Replaced fuse but still no power at gauges or ignition. Replaced "batt charge" relay with the horn relay (same exact OEM relay) and I had power at the gauges and pickup started fine.

Had no drops in voltage at the gauges at all for about a week after this. I figured the alternator probably was going bad and could not handle the AC cycling on and off so often and that this same AC cycling issue or the alternator were the culprit for the relay and fuse failure.

Checked AC High and Low pressures (40 low and 300 high when warm and 1,500RPM) with the pressures remaining very consistent. Captured some of the coolant as I read on this forum that the correct pressures should be 25 low 200 high). The frequent cycling continued. Cleaned out the evaporator by vacuuming (with soft brush to avoid damaging). AC still has frequent cycling.

Tried to limit AC use but had to use it for approximately a total of 3 hours during one day. All this time since the alternator change the voltage drop at gauge would only occur when AC compressor cycled on (to approx 12.5V) and would climb back up to a bit over 13V when compressor was running and back up to around 14V when AC was actually turned off. By the end of that day the voltage gauge was fluctuating a little low even when the AC was not on and dropping a bit below 12V if the AC compressor cycled on (during my testing).

The next morning the pickup again has no power at gauges or ignition. This time the "batt charge" relay was fine so I replaced the "batt charge" relay but I still had no power at the gauges or ignition (used a new relay and other relays from the vehicle which worked fine). Checked other fuses and found that the "IGN1" 10A fuse inside the cabin looked warped so I replaced it with another 10A fuse from the vehicle and I had power at the gauges and ignition again. The weird thing is that I tried starting the vehicle again within an hour (did not drive it or turn on the AC) and again I had no power at the gauges or ignition. I took the fuse which I thought was damaged and placed it back and the pickup had power at the gauges and ignition again! This last paragraph I cannot explain in any way.

Questions: What is the correct pressures for this vehicle? Could a bad alternator have caused fuse to blow and relay to fail? Coincidence that I have a possible ignition issue also? Do relays require to receive power for a little after replacing in order to function? Can the cycling on and off frequently by AC cause damage to the "batt charge" relay and/or fuse? Can the cycling cause damage to ignition fuse(s)? The AC could be expansion valve even if the pressures remain very steady? More likely to be evaporator causing cycling? AC switch in the high pressure line? I am gong to replace the AC switch anyway and thinking I may add refrigerant to bring it back to the higher pressures it was innitially at.

As you all have experience, not knowing is very frustrating and worrying when we can narrow down what the true origin of our issues is.

 

I can't speak to the AC, but if I were you, I'd be highly suspicious of your grounds, but more so your positive cables between the batt, alternator, and fuse/relay box in the engine bay. Corrosion inside the cables isn't unheard of. Piss-poor connections of the lead from battery to fuse/relay box in the engine bay (under the fuse/relay box) is not unheard of.

More than that, I'd be VERY suspicious of leaks into the cab integration relay/fusebox. Need proof? Yup.

 

AC cycling is normal at low ambient temps, ie, when its not working hard. This should have nothing to do with your problem.

I second that it's likely a battery cable issue.

 

+1 for electrical issue somewhere. I like the idea of shorts between battery cables/fuse box. @shifty` @Aerindel are there any common issues/failures related to ecm/ecu with gen1’s

OP I’m curious if the symptoms changed at all from day to day with temperature/precipitation fluctuations.

 

Thank you. I will pay attention as to whether weather affects the fluctuations. It has been steadily warm here. High 80s / Low 90s. Again, since replacing the alternator, there are no fluctuations at all aside from when the compressor continues to cycle on and off.
I forgot to add that the fluctuations are only at the dash gauge. With a multimeter at the battery posts the voltage is pretty steady at 13.7-13.8 even when the gauge at the dash is low from compressor cycling. If lights are turned on at the same time that both seat heaters are engaged and all windows lowered there is only minimal drop at the dash gauge as would be perfectly expected. Battery is holding its charge perfectly fine. I was not thinking it would be related to cables/grounds because, if I do not use the AC, there are no electrical issues at all on any other occasion. If anyone knows about the electrical flow as it relates to the voltage dash gauge and the AC, that would be very helpful.

Whenever something goes wrong, we are alert to little things that maybe were always happening (are normal) and we had not noticed before.
Could it be that some connection for my ignition is causing the issue now and then of not having any power at the gauges or ignition? However, this has only happened exactly after using the AC for a significant of time during one day and that when the AC was being used, the voltage gauge would fluctuate lower and lower and then remain low. The two times that I use the AC significantly is precisely when the next day I have the no gauge/ignition condition.

Leaks into the fuse box? Will look into it. I would have to remember whether I washed the vehicle the days prior to having no power at the gauge/ignition. Again, it was just the one failed fuse "batt charge". I believed the "batt relay" was bad because the gauge/ignition received power as soon as I replaced it the first time. However, the second time it happened, replacing the relay did not solve the issue and I found that the "IGN1" fuse looked bad. However, I was then able to reuse the relay which I had replaced the first time and have no issues whatsoever even with that one that I thought was bad.

When replacing a fuse, are there cases when the fuse has to be back in place for a bit of time before the the gauge/ignition is allowed to receive power? I ask because, its possible that the relay was fine the first time this happened. In both cases, I had power at the gauges/ignition somewhere around 5 minutes after removal and replacement of a fuse ("batt charge" 30A first time and "IGN1" 10A the second time). I doubt the answer to my question is affirmative because even when disconnecting the battery, the gauges/ignition are ready as soon as you connect the battery back up. I still suspect something AC related due to the voltage drops at gauge happening when using it and the issues with power at gauges/ignition happening the following day each time.

 

Aerindel, when you say AC cycling is normal. How often do you mean? On for 10-30 seconds, off for 10 seconds frequent?

Also, if any of you have a 1st Gen and can observe your voltage gauge as to how much and how often it drops when AC is in use, that may indicate this is normal and something else happens to be going on at the same time.

What does the voltage gauge actually read? I thought it was how much voltage is being sent from the alternator to the battery but the voltage at the battery posts is steady regardless.

Thank you everyone.

 

Yes, that is about normal. I can only saw about, because it's dependent on temperature and varies naturally with that. Currently its 40º here, mine cycles 5 seconds on, 60 off.....so not very useful for comparing with yours.

Checking my truck, the voltage gauge does not move when the AC clutch engages. The only thing that makes it noticeably drop, is the wipers and only by a tiny amount.

This does seem to support the idea that maybe the AC clutch is bad.