Dreaded trans. Failsafe prog.

[Oldmactech]

Doing about 60 yesterday and the abs/DSC light came one, pulled off to the side and trans.failsafe light came on and all I could do was limp mode. On my way to an important meeting. Switched off and back on and was able to drive the last Mike or two but no torque and didn’t shift properly. Got it back home and getting odd codes. All 4 oxy sensors, MAF low voltage , ICV mechanical failure.

Also 5A brief Power interrupter76, DME/DDE does not fulfill Torque request 3A no message from EGs control unit.

Suggested that I replace the battery but it’s 12.7 at rest and 14.17 running. Suggest to me that battery (less than a yr old) and the alt are good.

I also disconnected the ABS cable but no apparent effect.

I’ll check the fluid on Monday but I also smelled a burned smell but in heavy traffic, who knows.

Any diagnostic tips would help.

Thanks.


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[andrewwynn]

What you described is exactly the classic example of alternator failure.

Clear all codes and watch vBat real-time. Best if done with a graph to catch short dips or spikes.

Usually the first sign is abs trifecta followed by possibly misfire/engine failsafe then transmission failsafe.

If any or most of that happens then you can clear the codes and it acts normal or else, will reset on their own it's almost always the alternator.

When near end of life the alternator can go through a bad day a few times and back to normal but if you monitor voltage on a groggy m graph you can usually pick up on the voltage dips.

How many miles (hours).

Divide odometer by average mph (for me about 160000/25=6400 hours). I was able to restore my alternator for $20 with a kit of brushes and slip rings. When wife's failed at a very similar hour life, I just changed the brushes and the polarity of the brushes so the other side of the slip rings would wear as only one gets 3x the wear of the other.

Consider: odds of all those different systems having a problem or the one thing they all run on (electricity) being the source of all the problems.

[Oldmactech]

Kinda what I thought. Has to be electrical and I have had issues similar with an e46 that were fixed with a new battery.

Thanks. Reassuring.

Is an alternator rebuildable by a mediocre skilled shade tree guy?


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[andrewwynn]

Originally Posted by Oldmactech

Kinda what I thought. Has to be electrical and I have had issues similar with an e46 that were fixed with a new battery.

Thanks. Reassuring.

Is an alternator rebuildable by a mediocre skilled shade tree guy?


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Changing just the brushes is 2/10 difficulty. Slip rings 4/10 difficulty. It's easier than changing the alternator which is 5/10 or 7/10 (until you learn the nut insert trick)

It's very rare that a bad battery will cause problems while driving, it's usually that a new battery will mask voltage regulator problems buy acting as a voltage smoothing filter. Similar for a bad starter. As a starter starts to fail it takes more and more current to do its job, this will pull the voltage down do to resistance loses. A new battery will hide the problem and results in quick battery failure. Slow rpm long crank is a symptom of a bad starter not bad battery.

A freshly charged end of life battery will usually crank almost normal speed. (but may fail to crank 3 times in a row as the capacity is what goes away).

[Oldmactech]

Ok, terminology clarification.
Brushes=voltage regulator?

Nut insert trick?

Also, put my cheap scanner on it and both oxy sensors show 0 voltage.


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[andrewwynn]

Brushes are part of the VR. They run on the slip rings and how the armature gets power for the field windings. They are the primary wear part on an alternator.

The insert nut is a press fit steel nut that the main bolt for the alternator screws into. It's so tight a fit that it's extremely difficult to install when it's in its final position. Tapping it out to make even 1mm extra room decreases the difficulty level about 80%

It's possible to view the wrong type of O2 sensor and it will read zero.

[Oldmactech]

Thanks.

The O2s have functioned well for the 10k Miles I have put on the car since I have had it. Just wondering if that further indicates Alternator prob or something else. MAF is getting 1volt.


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[andrewwynn]

Can you read real-time vBat and better if you can graph it.

If you don't have a steady 13.6 or so, all bets are off

[EODguy]

Originally Posted by Oldmactech

Thanks.

The O2s have functioned well for the 10k Miles I have put on the car since I have had it. Just wondering if that further indicates Alternator prob or something else. MAF is getting 1volt.


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Once you've sorted out your voltage regulator test your MAF.
I have MAF issues all the time here (105f-125f) so getting a 1v reading on the MAF brings back the memories


The trick to checking your MAF is to tap the join (not loom connection) where the wire loom connects several times while idling with a screw driver handle (hard not breakable hard!) and if the engine stumbles it's time for a new one.

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[bnfaustin]

Originally Posted by andrewwynn

What you described is exactly the classic example of alternator failure.

Clear all codes and watch vBat real-time. Best if done with a graph to catch short dips or spikes.

Usually the first sign is abs trifecta followed by possibly misfire/engine failsafe then transmission failsafe.

If any or most of that happens then you can clear the codes and it acts normal or else, will reset on their own it's almost always the alternator.

When near end of life the alternator can go through a bad day a few times and back to normal but if you monitor voltage on a groggy m graph you can usually pick up on the voltage dips.

How many miles (hours).

Divide odometer by average mph (for me about 160000/25=6400 hours). I was able to restore my alternator for $20 with a kit of brushes and slip rings. When wife's failed at a very similar hour life, I just changed the brushes and the polarity of the brushes so the other side of the slip rings would wear as only one gets 3x the wear of the other.

Consider: odds of all those different systems having a problem or the one thing they all run on (electricity) being the source of all the problems.

[mention]andrewwynn [/mention] where was this beautiful reply 2 months ago when I paid close to $1K to replace my alternator, pulleys and belt :-). I could have saved most of that money with your reverse the brushes trick. VERY CLEVER, I will have to remember that one!