Hello, I'm new to this site, can anyone help? Overdrive does not function, I have checked the solenoid valve on gearbox, that clicks when 12 volts is applied direct from battery. No volts appear at solenoid when button is pressed. I have dismantled the switch on gear lever, with solenoid disconnected, 10 volts on one side, when switch is made, volts disappear from live side. Where do I look next?
- (#3294) Eric Beauchamp, 10 Jun 02
In this order check:
Main Switch connector
Computer Connector
OD solenoid connector
Fuse (Gauge)
With ignition on should have battery voltage to terminal +B of OD computer connector. If not then suspect a cut or short in wire or a fuse.
If there is voltage then check resistance at OD solenoid. If it doesn't read 13+/- 1 ohms replace OD solenoid. If resistance is ok check wiring for open or short circuit and check the wiring connector. If still no joy then suspect the computer.
HTH
Ian
- (#3296) Ian Dunse, 10 Jun 02
Ian
Thanks for a speedy reply, where is the OD computer located?
Eric Beauchamp
- (#3298) Eric Beauchamp, 10 Jun 02
I'm guessing but if the same as the Townace then it's the little black plastic box that slots onto the front of the gear shift mechanism. You'll need to remove the gear shift cowling to get at it.
Ian
- (#3323) Ian Dunse, 12 Jun 02
And in typical toyota fashion, it isn't really a computer, more a couple of diodes...
- (#3324) david miller, 12 Jun 02
Well exactly. People are eager to hang the name "computer" on any bit of electronics these days. Makes it sound sophisticated. It's actually more of a relay than a computer.
- (#3326) Ian Dunse, 12 Jun 02
Thanks Ian and David
It is indeed where you said, here is the outcome.
i) Couldn't identify +B terminal but battery voltage does appear on one pin with +10v on another.
ii) Checked all connectors as suggested, no obvious problems.
iii) The solenoid clicks if battery voltage is applied directly to it so probably OK.
iv) Opened the computer, it does seem a bit more complicated than a few diodes, but hardly a computer. No obvious signs of damage, (overheating etc).
There are several wires going to the OD computer so they are presumably sensing other areas of the engine, what, I do not know. (vacuum, revs ??). Being a bit stuck, I replugged everything, run it round the block and it seems to be working, at least it did for the weekend. Possibly a bad connector connection, I will feed back any further problems.
A WORD OF WARNING though, the switch on the gear lever is easy to remove and dismantle to check the contacts and wiring etc HOWEVER, note there are TWO SPRINGS inside, one provides the locking action, and the other provides the resistance to pressing. It is the first one that flew past my ear as I carefully released the clips on the switch. It's probably resting somewhere safe on my engine, where the little bugger is, I'll probably never know. Result, the switch no longer locks. Solution was to tape it closed which is fine for general driving but may cause a problem when I tow my caravan up hills on holiday. Perhaps I'll only use flat roads. shouldn,t be too difficult from London to Cornwall.
Sorry for the length of reply but you appear to appreciate feedback, good and bad and if it stops someone else loosing a spring, its worth it.
Thanks for the advice, I'll keep a regular eye on this great site in future.
Eric
- (#3398) Eric Beauchamp, 17 Jun 02
Eric
Yes thanks for the feedback. Just love it when a plan comes together. I almost inadvertantly dismantled the switch on mine once but stopped when I realised the potential for what exactly happened to you. Can't you utilise a spring from something else? As I recall it's nothing out of the ordinary.
Glad you got fixed up. Bad contacts are a common electrical fault.
Ian
- (#3399) Ian Dunse, 17 Jun 02
Continuing story.....
Went for a spin yesterday, and guess what, yep...no overdrive.
Does anyone know if there are any sensors in the overdrive circuit, ie vacuum, oil pressure, engine revs or speed etc (and where they might be located) that would ensure that overdrive only operates under the correct conditions. As I said in an earlier message, there are several wires connecting to the OD computer, they must go somewhere. Surely it doesn't just need +12V to operate.
It seems to point to either :-
i) a broken/intermittent wire (Need to know all components in OD chain to check this)
ii) a broken or intermittent sensor (as above)
iii) an intermittent solenoid (could replace if I could catch it broken)
iv) could over/under filling of gearbox oil give these intermittent symptoms, or in fact knackered oil? (could change oil)
v) could kickdown cable adjustment contribute to the problem? (haven't touched it so far in 2 years of trouble free motoring)
It would be nice to find the fault, and hence help others, rather than just replace things until it works, unfortunately my pockets are not bottomless.
Holiday looming, why do things only go wrong when you can least spare the time.
Thanks in advance, I know someone somewhere has the answer, probably Ian, as he seems to answer every other problem. (I know others do too)
Eric
- (#3423) Eric Beauchamp, 18 Jun 02
Eric
There is an overdrive solenoid and speed sensor in the circuit. I'll scan the section and diagram from the manual tonight and e-mail it to you tomorrow.
Ian
- (#3425) Ian Dunse, 18 Jun 02
Does our O/D actually have the speed sensor etc? I've never been able to find it on the speedo. TEMS- equipped townies have one for it, though.
- (#3429) david miller, 18 Jun 02
To whoever is following this thread ....
Just a word of thanks to Ian, who, as promised in his earlier post, has scanned & emailed me the relevant 6 pages from his manual.
This information I thought was unavailable.
To find people who will give their time & effort to help others is truly amazing.
I will use the information to try & sort my problem and post the outcome to anyone who's interested.
Once again, many thanks Ian, and others who offer their help & advice.
Magnificent
Eric
- (#3436) Eric Beauchamp, 19 Jun 02
Ian & anyone else following this
Sorry for the delay in coming back, the story so far...
I checked the wiring using Ian,s supplied info..
Battery voltage at B+ of computer module, but no voltage at solenoid pin.
Broke the wire at the solenoid itself and connected a new 12V feed direct from the battery, and the solenoid clicked.
With this temporary feed in place, took the bus for spin, and lo and behold, overdrive had returned.
Prime suspect is now the computer module, this I will replace and feed back the final (hopefully) results.
A final question, if I could be so bold....
If a computer can not be obtained in time for my holiday, next weekend, would it be ok to leave this temporary +12V feed in place until one is found?
Best regards
Eric
- (#3578) Eric Beauchamp, 30 Jun 02
Eric, feel free to use your temporary supply. I have never been able to find any other sensors in the system.
- (#3580) david miller, 30 Jun 02
David,
Is it possible that now Eric has bypassed the computer to get the feed to the O/D switch he could take it out of overdrive above the speed at which the autobox won't let it come out of overdrive, possibly overrevving the engine, not sure if I'm right on this one, but my understanding of the 'computer' (let's face it, it's only really a relay box) is that it stops 'downshift' at speeds that would endanger the engine. Any thoughts David, as I say I may be completely wrong. Regards Rob.
- (#3581) Rob Drinkwater, 30 Jun 02
Hi all
After confirming that the problem was at the computer end,I disconnected the temporary 12V feed to the solenoid and had one last look at the computer connections.
Whilst monitoring the voltage at the solenoid pin of the computer connector, (should be +12V with ignition on and O/D selected on gear lever), it showed 0V, hence no O/D.
On checking other connections in the vacinity, +12V suddenly appeared at the solenoid pin. Careful examination confirmed that a wiggle on the computer connector could provide and deny the necessary +12V.
Opening up the computer, careful use of a small screwdriver releasing the two clips on one side revealed the board. Close examination of the connector showed no dodgy joints, however I took the opertunity to resolder them anyway.
On reconnecting the plug, no amount of wiggling could I get the +12V to disappear.
A quick spin confirmed that O/D is restored.
Hopefully that is the end of it, with the only casualty being the lost spring in the switch. This is now taped in the permanent ON postion until a replacement can be found.
Can I take this opportunity to thank all who advised on this matter, particularly Ian, who, without his help and diagrams, I would still be overdriveless.
Hope this info helps someone else.
May the site live forever, as indeed I hope my Spacecruiser does.
Best Regards
Eric Beauchamp
- (#3596) Eric Beauchamp, 2 Jul 02
Nice one Eric.
Even more gratifying when it's not cost you dear - just time and patience.
- (#3599) Ian Dunse, 2 Jul 02