NEED HELP!!! - Truck went into "LIMP" mode

[boonsur]

Any good doctors out there?



While traveling down the highway (75mph), I let my foot off the throttle as I came up on a slower moving vehicle. My truck dropped out of gear, down into 2nd(?), and wouldn't shift out of that gear, even when accelerating from a stop. Could only drive 45mph, winding the engine way out. Before turning home, I quickly looked under the hood and checked the fluids, etc. Everything appeared normal. I tried turning the key on/off 3 times, but nothing flashed, etc. I did not try disconnecting the battery to clear any codes.



The (factory) gauges all look good, and there was no Service-Engine light.



Another note, I had just driven through a brief rain shower, but was back on dry road when the problem surfaced.



The truck is a 1999 2500 4x4, 4. 10 Auto. I have an EZ installed (w/boost elbow) and a K&N filter. Otherwise everything is stock.



I am now late for evening plans, so I won't be able to look at it until tomorrow. I'm just wondering how to go about diagnosing the problem.



!!!!!HELP!!!!!

 

[Rambling]

No expert...

If I remember, others have recommended removing 'add ons' to see if an engine problem develops.

 

[boonsur]

Anybody???



I'm wondering if somehow I created too much boost and the EZ box did not correct for it. (I did just put the silencer ring back in) Would this shut the truck down?



Are there any other faults that would shut it down without the Service Engine light coming on?



Could there be a fuel problem (I had filled up earlier in the day)?



Is there something in the transmission (govenor, etc. ) that could go suddenly bad and act this way?



Where should I start looking?



Will disconnecting the battery clear the code, and allow the truck to run normal (until the condition happens again)?



Do I have to disconnect both batteries, or will just one do the job?





Please help!!!

 

[Ron Bissett]

LOSS of Power?

Sounds like Fuel filter is about to clog up . Or lift pump going south. Keep on checking. LOL Ron in Louisville KY

 

[Cooker]

Randy,

Sorry to hear about the truck. Like suggested above, try removing the EZ and boost elbow. I wouldn't think you need to remove the K&N to troubleshoot this problem.



Maybe test the TPS??? I don't know if the TPS failed it would cause limp mode, but I suspect it would.



I know Bill K. was answering a question similar to this down in Munice. Maybe you should shoot him an email???



-Ryan

 

[Big MAK]

If the engine would still wind all the way up it isn't in "LIMP HOME" mode. Limp home mode will limit fuel delivery resulting in fairly low RPMs while still shifting through the gears. Sounds like your torque converter has lost fluid coupling or is cored out. The TC either needs more fluid in the TC or the TC is bad. Otherwise it's transmission related. Just my opinion; but it doesn't sound engine related, it's the transmission or TC. That's bad news I know.



Moving to Engine/Drivetrain.

 

[boonsur]

Still suffering

I'm becoming more convinced it's transmission related. Bill K. called (on a Sunday!!!!), and gave me a few things to check out.



I have gone through the fuses, connectors, etc. , with no aparent problems. I removed the EZ box completely (re-connected the MAP sensor), removed the boost elbow, and disconnected the batteries (left off for 1 hour), to clear any faults. SO the truck is now basically stock, except the K&N filter.



PROBLEM STILL EXISTS!!! My truck has gotten lazy and decided that shifting was just more trouble than it's worth. So I only have one gear to choose from. Makes it real hard to beat the Hundai's off the line (although the 45 MPH top end may still be faster than they are).



Anybody else have anything I could check out??? It would be a LONG trip to the nearest dealer I trust (1-1/2 hours away at highway speeds).

 

[R.ebel]

Sounds like the old sluce box needs to visit the hospital

 

[Cooker]

Glad to hear Bill got a hold of you. Is that great service or what.



What did he say. TC or something with the VB???

 

[boonsur]

Answers

I got my truck fixed last week, and thought I'd post the results for future reference.



Thinking it had to do with the transmission, I drove it to my transmission shop. They have an OBDII scan tool and only charged $39 to do the diagnostics.



Immediately, a "Bad Govoner Solenoid Circuit" code popped up. I talked with Bill Kondolay, who said probably the govoner soleniod itself, or a transducer had faulted out, since this is a common problem (he knew the part numbers for these off the top of his head).



However, after further troubleshooting, the guys found the "OVER-DRIVE/LOCK-OUT" solenoid had gone bad. Because there was a fault in the line, the PCM "turned-off" (cut power to) the transmission all-together. This "limp-mode" gave me only one gear, and no lock-up. (They tested by manually putting power to the transmission, and it operated (shifted) fine, with no over-drive).



Total cost for diagnostic time, parts, and labor was less than $400, but I am still only as good as stock (with fresh fluid/filter). BTW, they said the old fluid/magnet looked very good, no signs of any problems (39K miles - first service).



Hope this can help someone else someday,



Randy J.