Diesel Doctor

[Aftermath]

Trans will shift to 3rd but before 4th it goes into safe mode or 2nd.codes "29 and 87"

No power to lift pump. Is oil pressure switch in front of fuel filter housing?

Blowing black smoke when hard acceleration.code "78"

All help is appreciated so thanks in advance,

Chris

[Aftermath]

Ok, I think shift slonoids.

Anyone know if the oil pressure switch is in the lifter valley ?

Thanks in advance,

Chris

[JohnC]

29 is glow plugs and 78 is the wastegate solenoid, so they are not relevant to the trans issue. 87 points to one of the solenoids, but, IIRC, both solenoids have to be working to get 1,2 and 3, so it could be a red herring. How long does it stay in 3rd? What happens if you start out with the selector in 3? Get a scanner on it and see what the speed sensors are doing.

Oil pressure switch, also unrelated, should be on the back of the driver's side cylinder bank, near the head.

[Aftermath]

Ok cleared the codes and took her for a spin. Started the selector in 3rd. 1st and 2nd ok, but would only go into 3rd when I manualy shifted to 4th but trans would not shift into 4th and eventualy defaulted to 2nd. Code #87 Red Herring?
Thanks in advance !!

Chris

[JohnC]

[quote="Aftermath"] would only go into 3rd when I manualy shifted to 4th[/quote]

that doesn't make any sense! Are you sure it didn't go into 4th? Also, don't confuse the torque converter lockup with a shift.

I think you're going to need to get a scanner on it to see what is really going on.

[Aftermath]

When it shifted to what I thought was 3rd gear in the "OD position" 55 mph @ +/- 3200 rpm (realizing now it may be the t/c lock-up) I had to shift the selector from "D" to "OD".

My question is this; Does the gear selector have to be in the "OD" position before the T/C will lock-up, or does the lock-up work on pressure mechanically without electrical help? I replaced both solenoids about 2 years ago but I understand one can go bad nevertheless.

However, If the code 87 is shift solenoids and I am mistaking 3rd gear for the T/C lock-up, then it would look as if a shift solenoid is bad.

Thanks for your help John C, more knowledge for the forum !

Chris

[JohnC]

TCC lockup is controlled by the PCM through another solenoid. It happens around 55. I didn't think the shifter had to be in OD, but that's from memory. I don't have as much documentation as I used to.

If you depress the brake pedal slightly and the TCC is locked, it will unlock.

[Aftermath]

okie doke......located the ground for both A and B shift solenoids. Cut the wires at the harness, run the wires to the inside of the truck, will now run through all gears when grounded and hold the pressure, so it is not inside the tranny. My guess is that the trans computer is bad being that it will get third gear and default when it should go to fourth. So I think I'm going to throw a trans computer at it and see what happens.

Also, I need to change the valve cover gaskets (pouring oil). Any tricks that will allow me not to have to remove the turbo? The fuel lines look impossible to remove with the turbo in place. Also, this engine has 150k on it. Should I replace the injectors and glow plugs or check and re-install if good?

Thanks for your help John C

chris

[JohnC]

More likely a speed sensor is bad than the computer. you need to put a scanner on it and see what is going on. BTW, a scanner can manipulate the shift solenoids, too.

There are no gaskets on the valve covers. They use an RTV like sealer. You can get aftermarket gaskets, but the sealer works better. Let it set up overnight and don't overtighten the screws.

Replace the glow plugs if they are original. Newer ones are better. If the injectors have 150K, replace them as well.

[Aftermath]

'Brain storm" at the transmission shop said he could't get the motis to change the gears and said no power to solenoid 3-4. He said he thought computer too. GM dealer said that they have never heard of this problem. maybe it is a speed sensor, 40 bucks for both? Should I replace the speed sensors before the computer. like I said, we got it to shift through all gears by manually grounding the solenoids but the speed sensors may be telling the comp to default. However, it was shifting to third, just not fourth and eventually default, does that sound like a speed sensor. I'm not taking it back to 'brain storm" if you think it may be a speed sensor, then I'll throw the parts at it and see if it sticks !

Also, on the turbo side, should I remover the exhaust manifold at the head to get to the injectors, glow plugs, and valve cover gaskets? any tricks?

Thanks dude your awesome !

Chris

[JohnC]

You can throw money at it, or get a scanner on it. If you don't have access to one, consider http://www.enghmotors.com/

Also, flakey power to the solenoids, usually due to the ignition switch, can cause similar symptoms. The PCM monitors the voltage and current on the solenoids and will set codes if the values are out of bounds, indicating a solenoid that doesn't shift when it should. Monitor the voltage on the trans fuse for signs of fluctuation.

Pull the turbo off if you want, but not the manifold. Neither is necessary but some think removing the turbo is worth the trouble.