99 Rodeo electrical problems - locks, alarm and radio

[geotrash]

All,

I've spent a few hours searching through the forums to find an answer, but no one else seems to be experienceing quite the same set of anomalies as I'm seeing on my Rodeo.

History: Several months ago my keyless entry system stopped opening all doors and would only unlock the driver's door. No big deal, I just ignored it. Everything else worked fine. I've owned the truck since new and it now has 128,000 miles on it.

Just this week, the door locks started acting even stranger. It started with the alarm going off at random times while the truck was parked and locked, and now when I try to lock the doors either from the fob or the rocker switch on the door, all locks go down and then pop right back up. It's impossible to lock the car! I've also noticed that both interior and exterior lights pulse at idle, and the doors try to unlock themselves when the radio is turned on or off but can't because I can't lock them anyway.

The only aftermarket items I have installed are an Alpine CD player and door speakers.

Any ideas? I've read the threads about the possibility of a weak alternator, and mine is the original, but I hate to start replacing random parts if it will only mask a greater problem. All help appreciated.

Cheers,
Dave

[pharm_rodeo]

Well, you have to start somewhere.

1.Get alt tested
2.Test battery and check grounds
3.Check wiring


Electrical problems are a PITA with Rodeos.

EDIT:
There were several members who had their alarms go off randomly. Might want to search for that if you haven't already. GL

[geotrash]

Thanks for your quick help. I spent some time with an ohmmeter this morning checking grounds for the engine compartment and chassis, and all checked out fine.

Basically, I think it's either an alternator with a failing regulator that's causing the electrical system to pulse, or something is putting an uneven drain on the charging system, like the fuel pump surging. When the engine is running, the idler pulley on the serpentine belt is moving on the same cycle as the light pulses, indicating that the alternator is loading and unloading about once a second.

I think I'll go ahead and replace the alternator for starters, followed by the battery. If that doesn't do it, I'll start isolating systems looking for a short or unusual current drain patterns. If anyone is interested, I'll report back here with whatever I find.

Cheers,
Dave

[geotrash]

Replaced the alternator tonight and cleaned up the battery terminals. All seems well, except the locks still unlock when the radio is turned on or off. At least the surging has stopped. I'm out of ideas there except to replace the alarm module to make the locks and alarm work as normal.

Dave

[tnobori1]

Originally Posted by geotrash

Replaced the alternator tonight and cleaned up the battery terminals. All seems well, except the locks still unlock when the radio is turned on or off. At least the surging has stopped. I'm out of ideas there except to replace the alarm module to make the locks and alarm work as normal.

Dave

I don't know that I'll be much help. About two years ago I had the same problem with the random alarm and unlocking. I was finding myself jumping out of bed in the middle of the night and having to run downstairs to shut off the alarm (my neighbors hated me!). Also, my doors would unlock randomly - not in any kind of pattern like yours does. I was quoted $300 to diagnose the problem, so I took the easy way out and yanked to fuses for the alarm and doorlocks. I now have a manually locking Rodeo with no alarm... it's quite sad.

I did hear some advice once about finding the relay near the cargo door and placing a quarter behind it. My knowledge of electrical is terrible so I didn't pursue it. I hope you find an answer and please let us know when you do.

FYI: I changed my battery and that didn't help.