Toyota Repair Problems? Ask a Mechanic for Answers ASAP
Let me see if I can help. What kind of readings did you get when you ran your tests? They should be as follows:
1. At the alternator, the large Black wire should have battery voltage.2. The Green/Red wire should also have battery voltage. This comes from the 7.5 ALTS Fuse.3. Verify that the Red wire has 12 volts with the ignition switch on. This comes from the 10 amp GAUGE NO 1 Fuse.4. If the Yellow wire is grounded, the charge light will come on.5. The Blue(L) wire at the alternator that goes to the ECM should have 12 volts with the key on.
6. When the engine is started, the Pink (or Black in some cases) should have 12 volts and the Gray (sometimes Yellow) wire should have a square wave signal. If these are correct there should be battery voltage present on the Blue wire to shut off the charge lamp.
Electrical stuff is really hard to diag over the computer.
You checked all of the engine compartment fuses right? 10 amp GAUGE NO 1 fuse, 7.5 amp ALTS fuse? Sometimes a seemingly unrelated fuse will blow and cause all kinds of problems.
If the fuses are good it might be an intermittent ground issue. That would explain the two codes they pulled; the modules keep losing ground and triggering signal loss codes. Check your chassis grounds and your negative battery cable connection on both the battery end and the engine end.
I have also heard about 20 times that these vehicles don't respond well to re-manufactured or aftermarket alternators. I'm a big fan of re-mans because of the warranty, but apparently something in them doesn't work well with the electrical system on the Rav4. Would it be feasible to put an original toyota alternator on it? I know it's at least twice the cost, but that might be what it takes to get it going again.
No, the ECM on this model isn't "smart" enough to ration available voltage to each system because of a dying battery. However, on the subject of a dying battery, one with a bad cell could test fine with some battery testers but cause the voltage to the PCM to be irregular. The battery acts as a kind of second stage voltage regulator on Toyotas. If the battery has an internal short it could prevent the alternator voltage from reaching the PCM correctly. Which could cause all of the problems you are having.
There should be a ground at the fuse/relay box, and one on the PCM, in addition to the chassis ground from the negative battery cable.
No, I don't think those codes would indicate any electrical related problems in general. The p0705 indicates a voltage problem in the transmission neutral switch. The p0500 is an irregular voltage pattern from a speed sensor.
Not the way you are testing it. If you are running a jumper from the neg to the alternator housing and you know you have good batt voltage to the alternator on the pos side it should put out full charge. You are essentially bypassing the rest of the electrical system and eliminating any other module as a possible fault.
What if you pull the alternator and have it tested on a bench at the parts store? Does it test good or does it show diode ripple? What about the battery? Have you had it load tested with a good carbon pile type tester?
You should see around 14.9 volts at the battery terminals, or at the positive terminal on the alternator within a few seconds of starting on the multimeter. You should also see around 14 volts from the black wire which comes from the ECM B30 pin 50.
I know it's not the best option, but I think you need a new battery and another new alternator (preferably an original toyota). I just don't think yours is working correctly.
Some fuses are powered, some grounded, which means if it is a grounded fuse it should light a test light when the opposite end is on the positive terminal, and vice versa for a powered fuse. They important factor is whether both sides of the fuse are the same. The best way to test them is with a multi-meter. Check resistance across the two sides of the fuse.
The starter relay was casing the the alternator to not charge? That's a new one for me.
I'm glad you got it going!
So it will still run the starter but not complete the circuit for the alternator? I'm going to write that one down.
That's awesome! I'm sorry I couldn't be more helpful. Electrical stuff is tough to diag in person, not to mention over the computer.
I just wanted to check in and see if you needed any additional information on this question. I haven't yet seen a rating from you and was hoping to have helped in at least some way in diagnosing this problem.