No overdrive

[RobertGray]

Pretty simple to do if the mechanic has any chops.

Sorry to double post but I can't delete the first comment
Hi guys I need some emergency help. The truck is on the lift at the mechanic's garage.
We changed the solenoid and 3-4 accumulator spring put everything back and four quarts (3.75 litres) of fluid now the truck will shift from park to reverse and work in reverse but we cannot shift into drive.
He disconnected the shaft outside the gear box and we can't manually move the manual valve shaft fully out. I think it is in for park.
Two things I noticed when the mechanic was doing the work one the solenoid wires were routed over the valve body and not under it as in all the diagrams. We cut the old wire and ran the new wire as per the diagrams. The second thing was that there appeared to be only one spring when we removed the 3-4 accumulator housing. All the diagrams showed two. There was no sign of the smaller spring the clutch valve spring and plug that is detained by the boss on the accumulator housing. I was not watching the mechanic when he removed the housing but he said he was sure there was nothing there and we searched the whole place as springs can go flying.
I am wondering if the rooster comb was misaligned when he removed the accumulator housing, but it looks as though you have to remove something else to get to it.
Any ideas?

 

[cerberusiam]

It won't shift to drive or it won't engage in drive? If the you cannot move the shift lever all the way to the back where it almost touches the trans case you have something jamming the linkage. Was the valve body dropped completely and the front band adjustment check? Did he check full movement of the shift lever with the VB out? Two places that can jam the linkage is the front band strut falling out and the detent ball orifice wearing in the VB.

 

[RobertGray]

Many thanks for your quick reply, I went back to the garage and he had got the shifter working properly, he said there had not been enough fluid in it but I think he had jammed something. I test drove it and the shift 1-2-3 is working normally. The trouble is the overdrive still does not work.
The valve body was not dropped, we only changed the solenoid and 3-4 spring.
They are going to put the TPS delete kit on.

 

[RobertGray]

It won't shift to drive or it won't engage in drive? If the you cannot move the shift lever all the way to the back where it almost touches the trans case you have something jamming the linkage. Was the valve body dropped completely and the front band adjustment check? Did he check full movement of the shift lever with the VB out? Two places that can jam the linkage is the front band strut falling out and the detent ball orifice wearing in the VB.

Update.
The TPS delete kit did not work. After reading around I realised that when the mechanic tested the OD he did it on the lift and that is wrong. So I took the vehicle home and first thing I did was repair the plugin connector/pigtail to the OD. The live was hanging on by 4 strands and the ground was not much better. Then I followed your instructions here:-

"Easiest way to check if the problem is mechanical or electrical, mystery switch on the OD sense wire. The other smaller wire in the harness above is the OD sense wire, to enable OD all the controller does is ground that wire. If you scotch lock a wire to the smaller wire of the harness, run it to one side of a simple SPST switch, the other side of the switch to a known good ground (not the battery post, you want a chassis ground), when you flip the switch an complete the circuit OD should engage IF the solenoid is good and the OD unit is good."

I put a switch on the dash and connected it as you said. Now the OD works when I flick the switch, and I can at least get about without being restricted to 45/50 mph. It also means my repair to the pigtail is good.
However when I try it with and without the TPS delete kit (wired up the normal way, I have put terminals on the sensor/ground wire and dash switch wire so that I can change it to the dash switch easily) it still won't work.
The speedometer works normally so I guess the speedo sensor works.
The engine temperature gauge works normally, it is a little cooler since the thermostat was changed but that was done some time ago. Does it run off the same sensor as the OD module?
So I am out of ideas. Any help much appreciated.

 

[cerberusiam]

Does the odometer work and read correctly on a measured mile? IIRC, the odo and signal to the SBEC that the truck has wheel speed is driven off the ABS sensor on the rear diff. If it goes bad or the connector up on the frame loses connection it will impact OD operation. The SBEC controls OD completely based on inputs and it could very well be the issue but need to check the other things.

Trans temp sensor will also stop OD if it fails, make a jumper wire between the plug receptacles on the plug itself and check that harness to make sure it is no broken. Do the same with the rear diff sensor and see if you find any broken wires or contact issues.

Since the OD works with the mystery switch the mechanicals are all good, it is the aged wiring and maybe the SBEC that is the problem.

 

[RobertGray]

I am sorry, what do IIRC and SBEC mean?

Also what do you mean by make a jumper wire between the receptacles on the plug itself and why?

I have been checking the wiring for any obvious breaks/chafing but not exhaustively and so far nothing obvious. I did not know about the ABS sensor so none of that is checked. I have looked at the trans temp plug and whilst the wiring immediately into it does not look great it does not appear to be broken.

The odometer has not worked since 2012, I bought the new gears for it but the mechanic in Spain said that there did not seem to be sufficient power to turn the gears?

Many thanks

 

[cerberusiam]

IIRC - If I remember correctly.

SBEC - Single Board Engine Controller. That is what the computer in your truck is called, frequently called a PCM but that is way overstating it capabilities. It is pretty dumb.

A couple spade connectors and a short wire allows you to bypass the trans trans temp sensor to see if it is contributing to the no OD. If that circuit is open the SBEC won't command OD.