XSeries-forum

Hi all,

I appreciate the "Trans. Failsafe Prog" error has been covered heavily, but despite all the searching across these threads, I can't seem to find anything related to the issue at hand.

So, it's an E53 4.6is, 108k miles on the clock with new Yuasa battery (tested with multimeter, all good, voltage whilst running hovered between 13.8 - 13.9v).

However, recently the car has brought up Trans. Failsafe Prog more frequently (was intermittent before), and the only way to get around it, is to restart the car (literally startup the engine, idle, switch off and start again), after which the error disappears.

It has, on the odd occasion, decided not to start after pinging the "Trans. Failsafe Prog" error, the only way to fix this is again, to take the key out, wait a couple of seconds and go again.

This is a clear pattern - any ideas on what may be the issue, please?

Any help/advice would be most appreciated.

Trans fail normally appears due to low battery voltage but you say alls good there, when was the box last serviced?, it maybe a solonoid on the valve control body playing up which they'll check for you if you havent had the box serviced.....recommend service interval from ZF is 60k

I have a problem also with the trans failure warning.
It will always throw tfs fault if I try and start the car in the normal way : in Park, switch on and start car ,throws trans fault warning.
So the way I start is put in neutral and then start, always works with NO trans failure fault

Also neglected to say have had an gearbox service and oil change done within last 1000 miles.( Fault was their prior to the service)

Lez

I wonder if your Park position sensor is on its way out. It’s on the box itself so not the easiest thing to get to without lifting gear.

That being said, if it wasn’t detecting the lever being at ‘P’ that should inhibit starting anyway, as that’s only possible in P or N.

I think I will live the fault , thanks for the info.
Lez

Over the last 14 years I have had various trans fail safe modes on my 4.6. Absolutely everyone of them had bugger all to do with the gearbox. You need diagnostics to check wheel speed sensors. ABS module is a known failure item (repairable now a days) the gearbox wiring harness plug underneath needs to be checked for corrosion, it’s easy to get at and check the pin's. As does the g/b ECU. Don’t ask me why but remove the throttle body wiring harness plug and hose it down with contact cleaner and plug it in and out several times. If the g/b was working perfect before the failsafe then chances are it’s now not receiving the right information from one of the sensors or there’s dirty pin’s somewhere
My box failed at 175.000.miles. Had a rebuild done £3k.

Hi Petrol, I was plagued with this issue recently. My starter motor was slowly failing - unknown to me, and it would take about 15 - 20 seconds to fire up (diesel). During the cranking, if it went on too many times (numerous attempts) the TRANS FAILSAFE warning would appear, and the car was basically in "limp home" mode. Restart with a warmed up engine, and the warning would vanish, and the car drove normally. Until the next day...

Might I enquire as to how long your engine is cranking before it fires up? My new starter motor fires up in less than a second, and it's winter where I am (albeit a sub-tropical "winter"!) with no problems, and no smoke from unburnt diesel. Works perfectly.

Check out your starter.