Power Steering problem when driving

[Grimbo]

Evening all , first post in this thread but not on LC forums .....;-)
I have a 96 24v Landcruiser 80 that suddenly developed a power steering problem.
It has a 2 inch full OME lift with caster correction and fitted with 285 /75/16 BFG K02's.
All was fine until I stopped at a garage to put some air in a slack front tyre , checked pressure in the tyre's restarted and as I drove up the road the steering felt "strange" but as we were in Devon on holiday didn't investigate beyond visual inspection and wheel wobble /pulling on track rods etc , the 250 mile drive home was interesting as the steering showed a lack of self centring and was stiffer than normal.
I have checked steering fluid and pipes etc all are good.
The steering is speed sensitive as all those who have 80's will know.....now this is where I start to get puzzled, at start up and tickover with no movment the steering is light and as it should be , it seems directly I start moving the variable solenoid is being told to go to the fully stiff position which is from the W/shop manual with the least voltage supplied from the ECU , I think I have confirmed this by disconnecting the soleniod on the steering box and the steering is stiff , reconnect and at least while stationary the steering returns to how it's always been at tickover when not moving.
Anyone else had this issue ? where is the steering control ECU located ? my w/shop manual is for the earlier 12v so not sure if it was moved .
The only other cause could be the speed sensor but the speedo reads correctly and is rock steady.
As the problem developed suddenly and after a stop /start I'm thinking it's electrical and unlikely to be a bad connector or rubbed wire ....do the ECU's fail ? it seems they work on resistance so a resistor gone down would cause this .
Good to see some familiar names on here from another my past on another forum where little happens ;-) .
Any thoughts /ideas appreciated
Grimbo

 

[Grimbo]

So after a bit more investigation and given that part of the official Toyota w/shop manual fault finding flow chart is " try another ECU "... I think that's my next course of action.
Anyone had any dealings with the breakers who are on Ebay ? Good or bad ?

 

[Towpack]

One of the forum's members, Karl Webster also sells on Ebay and has a very good name for good used parts. If he see's your post I'm sure he'll respond or you could try PM'ing him.

 

[joinerman]

GRIMBO, Where have you been ? long time bud.

 

[clivehorridge]

One of the forum's members, Karl Webster also sells on Ebay and has a very good name for good used parts. If he see's your post I'm sure he'll respond or you could try PM'ing him.

To do this tap inbox (top RH corner) and start a conversation. In the recipient box just type Karl and his user name should pop up... click that and insert your message.

 

[StarCruiser]

Or just say @karl webster and the shop keeper should appear as if by magic.

You may not have enough posts to start a conversation just yet.

 

[Grimbo]

GRIMBO, Where have you been ? long time bud.

Good to hear from you too ,
been busy with work / life / doing stuff with Tanks etc , the Landcruiser has been it's usual reliable self until this problem , just clocked 170K . Have got away a few times , built a conversion / sleeping platform in the back and for the 2 of us + 1 collie it's perfect .
Good to find an active forum with familiar names.

 

[Grimbo]

Ok,bit of an update, I have just had 5 mins spare so crawled under the old girl and disconnected the speed sensor of the G Box .
Test drove and the steering as expected stayed the same as not moving so was light at 50 mph !
Thing is it still won't self centre so apply a slight lock and it will just keep that lock on as you drive.
I'm now beginning to suspect the hub pivot bearings ....if one has gone tight that will give the same sympton.
The investigation continues .
P.S have sent Karl a pm about parts and he has gone quiet......is it me ?

 

[Cptsideways]

I used to override these with a wire & a switch on my Toyota race car, same system. Might be worth a temp feed to see if thats what the issue is

 

[frank rabbets]

Presumably if the car holds a bend without having to turn the wheel without much force you describe the symptoms of light steering. If you think the reason for this non self return being tightness somewhere in the steering this is a conflict in statements ? I'm trying to work out what your problem might be but to bridge the switch with a wire as suggested might help you diagnose.

When my swivel bearings wore I could tell something was wrong when I had to remove the tie bar to lubricate the track rod threads for adjustment. I noticed that the freed hubs would spring/self centre to the dead ahead position as the bearing races had worn to this position and had grooves in them corresponding to the rollers. The factory preload made this return happen. I felt no difference on the road but presumably this would cause more self centering not less. I wonder if the problem lies with something changed in the lift you have.

 

[Grimbo]

Right ,
To clarify .....by disconnecting the speed sensor I have overridden the PPS system ....it thinks the vehicle is stationary so gives full power assistance.....this although sorting the heavy steering feeling has shown that the steering still feels not right with no ackerman affect .

Yes the car has a 2 inch lift and has 285/75/16 BFG AT tyre's but it has castor correction fitted and steered perfectly at all speeds sitting a steady as a rock at high motorway speeds for months after the tyres were fitted.

Something changed while we were on Hols in Devon .....it felt a little strange in the morning but after stopping and pumping up the tyres it immediately felt wrong - hence my thoughts it was electrical on the PPS system .
I'm now not so sure ,..... the hub pivot bearings would give a similar feeling of once you move away from the straight ahead position it's not self centring..... and given at speed the PPS will reduce the steering assistance this coupled with the increase in force required to move the wheels could well be whats causing the problem .
I just haven't had time to get it on axle stands drop the steering rods and track rod off and check the individual turning torques of the hubs .... will report back

 

[Grimbo]

It's getting to be like owning a Landrover ;-) ....2 days running I've been under the 80 .....had more of a look today and the problem is the steering box , it's gone tight .....the adjusting screw on top has sheared off inside....will post pics later .

 

[frank rabbets]

Pictures would be very interesting.

 

[Grimbo]

Ok , some pics...... The adjuster bolt has sheared which has let the shaft drop so everything was tight , with the box off the car I couldn't turn the steering box by hand , if I can get the parts then it should be a simple fix

 

[frank rabbets]

What the hell caused that? There's only a screw diver slot in the top. Also is the sheared off part difficult to turn? Can't see where the torque came from?

 

[clivehorridge]

Seems that although bad news, at least you've identified the problem...

 

[Grimbo]

No idea why it failed ,
Frank - yes the thrust bit left is free to turn , its a clean break not a twisting shear . We were going round some pretty tight Exmoor tracks and lanes with some very tight parts but nothing that should break the box , I've owned it for years so nothing recent should have caused it .
Bits on order from Toyota for £18 so no big deal , the needle roller bearings all look good and it was leak free .
I've also got a S/H box on the way from Karl so either way should be sorted soon .

 

[Grimbo]

So box from Karl fitted , Diff lock switch from Karl fitted and all good again .
Have to say service from Karl was very good , as a new poster I had not dealt with him and have a sceptical view of breakers , Karl restored my trust and got me sorted.
As for why the original failed ? not a clue ......the only things out of my control are I had new tyres fitted and tracking checked / adjusted a few months ago , it should have been a simple job as all the ball joints were recently replaced with new OE joints , fitted with anti sieze on the threads and new locking nuts/bolts on the rods, so everything is/was free to move with minimal effort.
I did find when I fitted the other box that the ball joints on the relay link were so aligned that they were both on opposite twisted axis , given we were doing some tight twisty full lock and axle articulation stuff i do wonder if this at some points was putting a downward pull on the pitman arm.

"New" box fitted

 

[frank rabbets]

Any chance of a pic of the broken bit ? (nice + clean lol).

 

[Grimbo]

Frank , pictures in post 14 .
You can see the end of the threaded bolt sticking through the top cover in-between my thumb and finger , and the other pic is the sheared off remains of the part left in the shaft retained by the little stake nut , this is free to revolve and has about the correct amount of end-float so it looks like whatever made it fail it wasn't a twisting shear .