454 chevy won't go into overdrive why?

dano · June 16, 2011, 07:13 AM

Could this be because of the lock-up and where is that located or TCC maybe vacuum. Anyone ever had this problem and how was it fix? Thanks everyone.

TommyM · June 16, 2011, 11:48 AM

Are you talking about the 1988 Winnebago on a P-30 listed in your profile?

Unless someone has done some serious modification, it has a TH-400 (or TH-475) transmission, which doesn't have either a lockup torque convertor or overdrive.

The 700R4 overdrive transmission available in the 1980's wasn't used in trucks heavier than 1/2-ton (-10 series). And the 4L80E heavy-duty overdrive transmission was introduced in 1991.

So it sounds like everything is working just as it should!

Tommy

tiinytina · June 17, 2011, 08:07 PM

our 1987 454 on a P30 in our Allegro doesn't have OD that I'm aware of.. what are you hearing or feeling that makes you think it isn't shifting?

Tina

dano · July 31, 2011, 07:03 AM

Yes Tommy it is, but it seems to be revving to high for some reason I have a turbo 400 transmission.Thanks Tommy!

enigma960080 · August 02, 2011, 08:06 PM

As an owner of an 89 Suprechief, I can tell you there is not TCC or OD in our machines... Its possible that play in the linkage or an adjustment issue may have you 'between gears or in Second when the shifter position indicated "D". Also, if you have not done so, pull the doghouse and check the tranny fluid

jkilbert · August 03, 2011, 07:45 AM

check for a loose connection or blown fuse, also check for vacuum leaks. when i had my '83 diesel suburban with the th-400 i had 2 episodes when it wouldnt shift properly. the first time my vacuum pump crapped out and i lost vacuum to the modulator on the side of the tranny. the second time was due to a plug that pulled out ofthe fuse box that according to the tranny guy also controls shifting....just 2 quickies for you to check

dano · August 05, 2011, 06:05 AM

It just seems to be revving to high for my liking.

dano · August 05, 2011, 06:06 AM

Did that already. Thanks1

GWINGER · August 07, 2011, 04:00 PM

Count your shifts, there are only two. 4:86 or 5:13 rear gear, it ain't no car baby!
J

jkilbert · October 18, 2011, 06:40 AM

one other thing and i know this sounds funny....check your clutch fan. if its not working properly it will sound like your engine is just screaming

Froggy1936 · October 18, 2011, 11:27 AM

That is a very good tip When my clutch fan went bad wile driving in Florida (locked up) The first thought i had was i just lost the tranny (due to loud roar) You can also check for gears by manually shifting after engine is up to about 3000 RPM this will also let you know if its slipping on shift Frank

Greywolf · June 24, 2019, 01:30 PM

96 Winnie Brave 29rq,95 chevy 454, Overdrive works, then after running some on road,starting from stop only goes into 2nd and engine higher RPM's. Pull over, turn off, open front instrument panel, ( ALT FUSE BLOWN ) 20 amp, blows again. NEXT replace with 25 amp. Start off again. Got to campground, parked. ok.
Trip leaving, exiting campground, BLOWS FUSE......Replaced with 25 amp,start off again. ran about 1 1/2 hrs. comes to stop light, start off , BLOWS FUSE. Replace with 30 amp....... another 1/2 hr and got home......
Last year repairs, Previous replaced starter switch above steering column. took care of problem last year.
Previous years House Batteries problem solved. I have owned for 6 years, spent over 5k on fixen things.
I now keep a supply of fuses. PLEASE HELP

ErikTande · June 24, 2019, 10:44 PM

You might have lost 3rd gear. Happened to me on my 1985 p30 two years ago. I ended up having to get the tranny rebuilt.

Does your reverse work properly or does that feel like it's slipping?

Rickf1985 · June 25, 2019, 10:34 AM

You keep stepping up to higher and higher amp fuses and you will find the issue, a burned to the ground RV due to the wiring harness going up in flames. You obviously have a problem in that circuit and I would guess that if you are now blowing 30 amp fuses that the wires are cooked over the entire length of that circuit.

tmsnyder · June 26, 2019, 10:55 PM

Just jack up the insurance and put in a 50 amp fuse, you'll have a new RV before you know it

Just kidding, you better track down the source of that short before you burn the rv to the ground. The fuses are sized on purpose to match the wires that they feed power too.

wae · June 27, 2019, 07:55 AM

Also, which fuse is it that's blowing? "ALT"? I don't see a fuse with that label on my wiring diagram, although my chassis is a couple years older. If it's a fuse for the power coming from the alternator then #1 I thought that should be a fuseable link not a fuse, and #2, that would typically be a fairly high amperage fuse.

Job number one would be to find out exactly what amperage the General wants in that fuse position and put one of that specification in place to see if it blows (or if it's one you've already tried).

If the correct-size fuse still blows then you have something in that circuit that is shorting out or otherwise drawing power beyond its design limits. So job two would be to identify what circuit that fuse is protecting and find all the components on that circuit. A chassis wiring diagram would be helpful for that step.

Once you know what is on that circuit, we've got to find out if it's the wiring harness itself or if it's one of the devices attached to the harness. Depending on the circuit, sometimes you'll just know what device is likely to be faulty and on others you start out by disconnecting everything and seeing if the circuit still blows. Then plug things in one at a time until the fuse pops. If we are, indeed, dealing with a main off-the-alternator fuse, and the correctly-sized fuse is blowing in that, it's a little bit trickier since that fuse is effectively feeding everything on the coach if/when the battery isolator is set to dual battery mode, but it's still the same basic process. Just don't try to run the coach without at least a battery connected to the alternator circuit.

There's a lot of work to do, but it's all fairly simple troubleshooting, really. If you can start out with exactly which fuse is blowing, we can go from there. As far as the transmission is concerned, that should be a 4L80E, right? If so, the "E" means electronically controlled so you've got a transmission control module floating around in there somewhere. If that TCM cannot communicate with the transmission, it will go to a sort of limp mode and revert to second gear only. So if the TCM is shorted out somehow, or if the wiring is chafing and causing a short, or if a solenoid in the transmission is failed then you're going to pop the fuse, lose power, and once Major Tom can't communicate with ground control it just floats around in its tin can staying in second gear.

Greywolf · July 03, 2019, 09:06 PM

OK, Today started with 020 amp fuse "ALT" fuse. Mines a 96 winne,but a 95 chevy chassi. Will ck on 4L80E.?Tranny.

Only blows this fuse.....
went aprox 6 miles not busy type streets to get to gas fill up, next to check air at Schwabs then onto highway 9 and blows the 20 amp. pull over , Replace with 25 amp. go aprox 1/2 mile when shifting into 3rd it blew fuse again. YES I PUT A #) in just to get home again........
I'am not sure if I had the clutch fan work done or not. have to check repair paperwork.
I know it's not good to put a higher fuse in.....

What is T.C.M. , T.C.C. .

from responses
Thanks Greywolf

Rickf1985 · July 04, 2019, 04:56 PM

Torque converter clutch. It sounds like you have a short in the harness in the trans or one of the relays.

tmsnyder · July 04, 2019, 05:11 PM

TCM would be Transmission Control Module, the 4L80E is an electronic controlled transmission ( a great one too).

You might want to think about taking this to a trusted mechanic. The engine and tranny is a standard truck setup, any shop should be able to troubleshoot that for you.

Before you do though, drive it up on some 2x6's, anything to get a little more height. Or don't if you don't need to. Chock the wheels. Lay some cardboard down and crawl under there. look at the wires coming from the transmission. Inspect them for chafing where they might touch the tranny, the frame of the RV, anything metal. Follow the wires to the TCM. At the TCM, look at all those wires for pinched or chafing wires.

Your time is free and you might find the problem. You might get off with only a few wraps of electric tape.

tmsnyder · July 04, 2019, 05:13 PM

Should they just take it to a transmission shop to diagnose it?

Quote from: Rickf1985 on July 04, 2019, 04:56 PM
Torque converter clutch. It sounds like you have a short in the harness in the trans or one of the relays.

Rickf1985 · July 04, 2019, 05:24 PM

It has been so long since I did one of these I forget which wire you can unplug on the transmission to eliminate the torque converter lockup. If that stop the fuse blowing then you know the issue. Google "E4OD lock up problems" and see if it gives you the wire. I am not up to dragging out my book right now.

If he takes it to a shop the first thing they will tell him is that he needs a rebuild, Which I seriously doubt.

udidwht · December 08, 2020, 05:31 PM

With respect to the 4L80E....

The wiring harness under the pan is the likely issue. It had an issue cracking allowing fluid into the connector. Do you see ans fluid at the connector on the side of the trans You shouldn't. There are very small mill-amps flowing thru the connector. Any fluid will short them out. If you replace the connector replace the shift solenoids (A & B) and turn the force valve clockwise 1/2 turn (small allen on end of valve). Then clean the connector with electronic parts cleaner well. The connector was updated by GM years ago as its a known issue that had a (T-Bulletin) sent out.

Another culprit...the ignition switch at the base of the steering column. A lot of different items pass thru this.