Parked it for 3 months, now 2nd gear only

[ees]

So I parked my '94 suburban just before Christmas and have not driven it since. I started it once about 6 weeks ago and let it run for about 15 minutes. Today I fired it up ironically to dispose of an extra 4L80-E core that I have on my trailer. At once it did not feel right as it took too much pedal to start moving forward. I figured it had sunk in the ground or something. I hooked up the trailer and headed down the road and it was obviously only giving me 2nd gear.

I pulled over and disconnected the trailer just incase it had a short or something, but this gave no change. My fuel guage was going kind of beserk, but it was doing that sometimes last fall as well.

The truck was harder to start this time since the batteries were getting low, but the voltage guage was reading just under 14 V once the truck was running. I looked this up in my service manual on page 7A-17A-33 and it gives the following:

SECOND GEAR ONLY

Possible Codes
- 24 A/Transmission Output
Speed Sensor Asm.
- 53 System Voltage High
- 75 System Voltage Low
- 81 QDM & 2-3 Solenoid


I didn't get any check engine lights while driving. I have it hooked up to my trickle charger right now. I took today off work today in part to take this core to a local transmission shop to get rid of it, so this is rather demoralizing. If anyone has any thoughts on this please let me know!!

Thank you

[joem]

I found the same problem on a 91 6.2 with the 4l80e the fuse was junk for the pcm. Limp mode is 2 gear only any brake or abs light on?
Joe

[ees]

No warning lights on. I will check the fuse, good thought.

[JohnC]

Ignition switch is a common cause for this behavior. There should be a fuse labeled "trans". Check the voltage on it. If it is low when the PCM does its self check it'll set limp mode. Probably sets codes for both shift solenoids and TCC solenoid. Gear indicator, speedo, tach and some other instruments (fuel gauge?) are on the same circuit

[Mark Rinker]

One of my '94 plow trucks did this a few years ago after being parked for most of the summer off-season.

Pulled each fuse, treating spades to coating of dielectric grease. Recharged batteries, cleaned up terminals. Cleaned all chassis grounds, sprayed electrical connection at transmission with WD-40 to displace any water in the connection.

Problem was resolved.

[ees]

Ok. This confirms my hunch...electrical. Better than needing a tranny. I guess I will start going through the chasis grounds and cleaning them up. A previous owner made a mess of some things under the dashboard so I will make sure that is all good too.

I did check the trans and ECU fuse and they looked good with no corrosion or the like, but I am sure my chasis grounds are not ideal.

Thanks!

[ees]

I was thinking about it more and I have had problems with my trailer connector in the past. I tried to clean it up last year and I rewired most of that end of the truck. I guess I will just trash it and get a shinny new one, especially since Northern appears to have it for $8. If I realized that before I would not have tried to clean it up before.

[ees]

Just to let you know my outcome. I left the truck on my baby trickle charger for almost 2 days (swapped batteries once even though it is not really necessary). Changing nothing else I took it for a spin and it works just like normal again. That sure is a load off my mind. I did by a new trailer connector since mine is nasty.

I guess the moral is drive the thing more often.

[Robyn]

The batteries being low were a major blow.
Now the side terminal cable GM uses are problematic at best.
The cables corode under the ends where you cant see it.
Also the ground cables will corode at the ends that mount to the block.
The alternator on the 94 charges the left battery and then the cross over cable brings the power to the right battery, which by the way is the one that feeds the truck.

Do yourself a real favor and replace all the cables. Both grounds, the cross over and the main feed.

The main feed cable actually has two parts to it, the heavy cable that connects to the starter and the smaller wire that feeds the terminal box on the right firewall.
The small wire runs behind the starter and around the back of the block and up the firewall.
You can just cut thaqt old small cable loose and run the new one around the top behind the air filter and in that way to save a lot of work getting it back up behind the engine.

Replacing all the cables will go far in assuring that this issue does not happen again.

If your Volt meter was going goofy its most likely a connection issue.

Get GM original cables as most of the parts store stuff I have seen is junk.

**TECH TIP** to access the heavy cable at the starter, remove the right front wheel and undo the rubber splash apron on the inner fender, poof easy access to the cable and the starter terminals.

Another good idea is to rewire the primary terminal of the starter (Solenoid trigger) through a Ford starter relay mounted behind the right battery on the fender.
Use the original solenoid wire to trip the solenoid and wire the supply directly off the battery. Run a new wire to the solenoid from the relay.
This takes a tremendous load off the ignition switch and also insure good current flow to the solenoid to get it pulled in and locked.
I have seen solenoids on these rigs fail due to poor current flow through the system.
If the power to the solenoid is low the system suffers a "Brownout" and will toast the starter as well. (Been there done that)

The solenoid does not pull in tight and the contacts will start arcing and then the connection gets poor and the amp draw goes though the roof resulting in a slow starter and eventually results in the starter burning up.

Had this happen to two 94's last summer, all in less than two weeks.

Hmmm fixed both the same way, unfortunately it cost me two starters.

Good luck and glad you got it going.

Let us know

Robyn

[ees]

Thanks for the suggestions! I have changed some of the cables already a year or two ago. I used welding cable which I like because it is so flexible. I really ought to follow through with the other items you discussed.

Thanks!