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80 Series Diesel TPS Guru's Required

Posted: Thu Apr 07, 2011 4:39 pm
by Surfin Alec
Hi all,

After my motor rebuild this week I am going to try to fix some bugs that have been bothering me for a while.

My cruise is playing up ie: when turned on and set, the throttle will go flat on, then off a couple times and then cancel itself and I get a flashing cruise ligt on the dash.

My auto is also not shifting as it used to, ie: it up shifts through the gears too quick and dosent kick down as it should.

Its like the cruise and the auto dont know where the throttle positon is.....

After a bit of nutting and yapping to some "expert mates" I think the throttle position senson is playing up. It sits on top of the fuel pump behind the boost compensator.

All the searching on the net only shows how to diagnose petrol TPS's that look different and have 4 wires. My diesel TPS has only 3 wires. The manual only shows how to set it up using a 5v supply and a meter, nothing about diagnosis or testing.

Any info, links, help appreciated.

Cheers,

Alec

Re: 80 Series Diesel TPS Guru's Required

Posted: Thu Apr 07, 2011 5:54 pm
by oldmate
I have a similar automatic problem, but mine is the 1fz petrol

The TPS check is mentioned in the chassis manual, and the procedure which i assume for both engines is

put a volt meter + on Tt terminal, - on the E1 terminal of the diagnostic plug which is in the engine bay on the passenger side firewall

With the engine off and ignition on, open the throttle. The voltage should rise in steps from 1 to 8 volt.

On another note, the auto trans computer has an error check system similar to an efi engine system. There is a specific code on these autos for a faulty TPS (or wiring inbetween). If the computer logs a code it tells you it has done so by illuminating the overdrive off light regardless of the button position.

On mine the light doesn't come on, even when i know it should be logging an error (such as when i disconnect the solenoid plugs on the gearbox). This leads me to believe the problem is with the transmission computer, or a wiring inbetween considering that an actual faulty TPS would also trigger a check engine light not to mention an obvious engine performance issue.

I'd be interested to know how you get on. Although I have managed to get around my shifting problems by shorting the low range switch. this selects a different shift pattern that changes gear based on speed rather than throttle position. But I don't have cruise control so that won't help you ;)