Trans in limp, no alternator charging, what gives?

Bobcat698

Bobcat698

Pure Diesel Power
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Apr 24, 2006
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On the way to the shop this evening my 99 24v shifted out of overdrive and went to 3rd gear, and would not shift back to overdrive. I was just about to the shop so I passed it off as a fluke as my TPS has been acting up on me.

When I left (at 3AM) I noticed the volts weren't where they were supposed to be and that the truck started out in 3rd gear (limp mode).

I have tach, speedo, & all gauges, and cruise works, but I have no overdrive and no alternator charge.

What gives? Thanks in advance!
 
I am wandering if you have an over pressure? Jumper the tranny relay, and see what happens. On the 1999 can you retrieve the codes on the dash? If so cycle the key on 3 times and get the code.
Do you have the VBA from haisleys in it? Or just a diode or resistor?
 
zstroken said:
I am wandering if you have an over pressure? Jumper the tranny relay, and see what happens. On the 1999 can you retrieve the codes on the dash? If so cycle the key on 3 times and get the code.
Do you have the VBA from haisleys in it? Or just a diode or resistor?
Click to expand...

I have the 3 wire VBA, from Goerends.

That doesn't explain the alternator not charging though.
 
SAme thing happened to me. I found that the alternator actualy powers the Transmission control relay in the fuse box under the hood. I believe its a blue wire from the alt thats powering it. HAve you tried a paperclip to jump the 2 in a row horizontal prongs where the relay sits? I just had a bad connection that kept me in limp. I just had to bend the prongs from the relay to get out of it.
 
Bobcat698 said:
I have the 3 wire VBA, from Goerends.

That doesn't explain the alternator not charging though.
Click to expand...

Check your alternator Fuse under the hood. I had one blow once and I lost charge and the gauges all started going out and truck ended up dying since the ECM wasent getting enough power to operate.
 
I didn't click about the alternator not charging. PCM may have a higher voltage requirement than the ECM. Good suggestions on starting with the fuses.
 
zstroken said:
I didn't click about the alternator not charging. PCM may have a higher voltage requirement than the ECM. Good suggestions on starting with the fuses.
Click to expand...

Yeah and that was with ny 99 5spd so I didn't have any PCM issues like Garrett is experiencing.
 
I jumped the relay in question. No change. The alternator fuse is not blown.
 
It's PCM problem,

Voltage regulator is built in and if it will be damaged, high voltage will also kill PCM (ther is no high voltage protection)
 
How much is your tranny 5 volt circut actual supply voltage?
 
Does the OD on off light work? Cruise seem to work. IF the PCM is fried you will see a no bus in the instrument cluster. Friend just lost the ground on his PCM and had a no bus in the instrument cluster. AC working? It is controlled by the PCM.
 
On an 01 it means "no communications bus"

If the OD works then your PCM isn't completely toast. Does the cruise work?

See if you have 12V at the tranny relay that supplies the tranny. Check for 5V out of the PCM.
 
Speedo and all are from the PCM, so I don't think it is completely toast.
Plug a DRB or a snap on into it.

Do you ahve any codes?
 
Check the 12V to the tranny relay. Make sure you are supplying it with 12V.
I would say your PCM is behaving because that is what controls alot of the functions that still work. Possible bad alternator?? Done anything electrically to if in the past few weeks?
 
Nothing electrical lately.

Get this, with stock relay in place, trans is in limp.

With jumper in place, trans doesn't limp.

No alternator yet though.
 
I don't know if the 99's will display the codes will they?
Is it the odometer saying no code?

Even if the PCM is limping the tranny the PCM will usually PWM the ground on the gov solenoid. Will the convertor lock up with the PCM and will it shift to OD???
 
Yes, it shifts to OD and locks up with the jumper cable in place of the relay.

I have a code reader. No codes.

I got a Snap-On scanner.. we had a 1693 code and tracked it to a charging voltage too low.. Ran all the tests.. Points to a PCM. I will have another PCM in the morning.
 
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