TCM troubles, Mazda5 (20 S) 2011 with iStop - Battery tray removal

kiwironnie

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Mazda 5, 2011
My Mazda 5, 2011 (Japanese import into New Zealand) is intermittently going into 'limp' mode with a U0101 diagnostics code and AT lit up, indicating communications with the TCM lost.
General advice seems to be to check the wiring connections to the TCM, ground continuity etc.
However I'm having a hard time figuring out how to access it, particularly as the vehicle has iStop, so a somewhat different layout under the bonnet than other Mazda 5 models without iStop.
The TCM appears to be under the battery tray bolted to the top of the transmission, but can't access it sufficiently without removing the battery tray.
The workshop manuals that I've been able to get hold of only show a layout for a single battery, with corresponding steps to dismantle, whereas the dual tray is very different, so I'm having a hard time figuring out how to remove it.
It's pretty straightforward to remove both of the batteries, and unbolt a small squarish fuse/relay box (not the main one) top left of the tray (the PCM shown in the manuals must be mounted elsewhere), but after that I'm kind of stuck trying to remove the tray itself.
Some assistance would be appreciated on how to remove the dual battery tray. What other parts if anything need to be removed first and what bolts, apart from the 3 at the bottom of the tray?
Thanks guys.

PS - It's clear now that the entire top part of the battery tray separates (is supposed to), to free the thick wiring loom into the tray. After a bit more effort I've released that top part. Had to release it from 2 lugs on top either side, by levering upwards, then sliding it to the left to release most of the clips at the bottom holding it to the bottom part of the tray). However there's a final plastic latch mechanism on the left bottom edge that keeps it attached to the bottom part of the tray. The trick to release this was to slide a hand down and get a finger onto a wedge shaped lug underneath the lip there, pushing it in (compress it so it fits into the hole above) whilst pulling the top part of the tray up. Two fixings holding the thick loom to the front of the tray can now be squeezed and pushed out, exposing (just) a 4th tray fixing bolt, in addition to 3 others at the bottom of the tray. When these are removed the tray comes loose but is still prevented from pulling entirely out by a stiff plastic tube firmly holding the thick wiring loom partly over the tray. However the TCM can now be accessed (although with difficulty) and its plug removed for testing.

TCM ground pin(s) connections tested good. Haven't yet checked connector pin voltages. It's looking increasingly like a faulty TCM, although the fault appears intermittently, goes away after a period, after which the fault code can be cleared. Am reluctant to replace such an expensive part when it's not yet clear that it's the problem.
 
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Am in nz and having exactly same problem except I bought the Mazda made Nissan lafesta highway star 2011 Had it 3 years now and has ran like a dream except for the fan belt snapping a year ago bn trying to fix with little knowledge of cars did you manage to get it fixed yourself I have remounted tcm yip that battery tray had me tearing my hair out but the transmission mount was even tougher just using a hand rachet I must say. Tried the transmission reset suggested by vehicle freak site which is specially for Mazda 3. Well worth trying I Checked the numbers on my tcm and put it on Google goggles they are indeed the same tcm as the Mazda 3 of that year this at reset on vehicle freak worked temporarily and got lights off dash that day only for them to come on and off intermittently whilst making a slight resistant judder but came back on and can't get it off now what an absolute nightmare it is getting to the bottom of this problem anyone got any suggestions for the diagnosis of this. I took her into auto electrician locally for obd and diagnosis but all I got was the dreaded code u0101 and a 2.5 k quote for replacement of the Hitachi batteries which only needed to be charged up to bring back to full health. What a con artist ! Probably done days of research now to get a working fix but still had no joy any suggestions greatly appreciated. Also people might like to know they have brand new Mazda tcm units on Ali express for the great value price of 200 dollars plus 65 postage so may order one of those if it comes to it as don't want an old second hand burnt out unit for twice the cost
 
Difficult job took me most of day and had to get half inch rachet and socket set to get the torque right but if I can do it as a complete novice on a tight budget in a country about as far from home as possible would expect remounting tcm to be light work for the more mechanical minded. Was a great sense of achievement and a confidence boost even though u0101 still coming up I Will be doing whatever am able to do b4 going to the garage in future
 

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