Bongo auto gear box issue - Not changing into top gear

[AndyMoule]

Hi All. My wife & I were so loathed to sell our Bongo, that we have had for the past 5 years, that we exported her to Australia when we moved 2 years ago... brilliant plan until you realise that no one knows the first thing about Bongo's here. I am rather hoping that you fine people will be able to help out.

After blowing the cylinder head last year, the Bongo is now having gear box issues. It started on a long road trip about a year before the cylinder head issue. Got the classic signs which I believe are associated with Solenoid problems with the hold light flashing and Bongo not switching into top gear. This resolved itself after a couple of days and we didn't have any more issues until the head blew 8 months later.

Anyway, got the bongo back after 2 months off the road having the head replaced, and when I eventually got it onto a highway I noticed that top gear was not engaging but the hold light was NOT flashing. I did the diagnosis code test with a piece of wire but no codes were returned.

Seems to be fine in the first three gears (maybe a little slow with its pick up off the lights) but apart from that... I was going to order a new solenoid pack but wanted to see if you fine folks had any other thoughts first (as obviously flying parts half way s across the world to find they are wrong is not ideal).

Thanks in advance for any help.
Andy

[Simon Jones]

5 years of Bongo ownership and this is your first post. Where have you been man?

A good cheap place to start with any transmission issue is to drain the ATF, drop the sump, and clean the filter. There is a magnet in the sump to catch all the swarf so that should be inspected and cleaned. The state of the fluid is also a good indicator of the overall condition of the gearbox. It should be a clear red colour, but if it contains bits or smells burnt then it is overdue for replacment and may indicate the friction surfaces are past their prime.

There are a couple of other Bongos in Aus and several in NZ too. In terms of spare parts, you are a lot closer to Japan than we are, so you could order parts directly from Mazda.

[Northern Bongolow]

this fan switch in the pic link below, mounted at the rear of the drivers side of the head, just above the starter motor it controls the fan switching point, the glow plugs, in fact most of the temperature switching around the engine including the cold start solenoids.

http://www.igmaynard.co.uk/bongo/forum/ ... ch#p618166.

the sender itself can give wrong signals to the ecu, check the wires to it, and see if the end is wobbly.
when the plastic end wobbles it alters the resistance readings so everything goes wonky----fit a gen mazda part.

this may have led to your head failure in the past if the fans are not triggering at the correct time/temp.

this part is about £40 and is available from the bongo fury shop, or dirrect from mazda and other bongo spares places, and easy to post.

there is also a temp switch inside the gearbox, both these things affect when and if the gearbox selects top gear as it will not do so until the gearbox is warmed up.

i would also check the fuel filter and the banjo filter as the engine working hard/struggling will also make the gearbox (kick down or stay in a lower gear).

[AndyMoule]

Hi Simon & Northern Bongolow,

Thanks very much for the speedy replies. I will do an oil change on the gearbox. Was going to use this guys video as instruction. Does it look correct?

https://www.youtube.com/watch?v=JKScm-JdKlI

Regarding the fan switch, do you have a photo or engine diagram of what it looks like and where it is. In fact, is there a good diagram / overview of the bongo engine any where as i am a total Muppet with this stuff. Very happy to do stuff myself but any help to ensure I don't accidentally remove the steering wheel is great.

Cheers

Andy

[dave_aber]

Engine overview pics are available on the wiki - click the link in my sig below.

[mikeonb4c]

You could ask bf member Alacrity (geoff) if he would consider a small fee for advising a local mechanic on ordering and fitting? Geoff is an autobox specialist who has a Bongo.

[wonkanoby]

funny he has a sump plug as mine does not

one of the main reasons i bought a pela pump

[Simon Jones]

He has the 2 litre petrol version.

[briwy]

Might not be relevant in Oz but we has the same problem last year. It turned out to be water and dirt in the electrical connections on the side of the gearbox.
At least one of these connections faces forwards and in our case I suspect what happened was that in deep snow water was forced into the connector body.
Taking apart, good clean and hefty doses of WD40 solved the problem. Might be worth a try.

[Alacrity]

Oil & filter change/clean will NOT fix this fault.

Does it have gears 1-2-3 & are they shifting late? If it does & they are it could be the TPS is way out of adjustment after the head issue. It is this & the output speed sensor that determines shift points. No codes only mean there are no ELECTRICAL issues. Dirty connections can be a cause but I would expect to see the HOLD light flashing as it would cause an electrical circuit fault.

If it were here - & it aint never going to be clearly, I would put a set of test lights on the external solenoid wiring to see it the ECU is commanding 4th (only after checking the TPS), if the lights indicate it is then you have an internal issue - possibly solenoids hydraulically failed - if the lights don't confirm 4th gear commanded then your issue is external.

[AndyMoule]

Again, thank you all for the input. Awesome community.

Alacrity / Geoff - It does have gear 1 to 3 and they may be changing a bit late. Sometimes feels like a bit of a jerk when changing from 2nd to 3rd. TPS = Throttle Position Sensor?

Is the output speed sensor the same as the engine speed sensor as I was told to check this as well?

Dave - Photos are a great help (I know where the TPS is now for a start).

Can anyone point me in the right direction for the output speed sensor as can't see it on the wiki

[Alacrity]

If the vehicle is 4WD then the output sensor will be on the transfer box I suspect, it not it will be on the tail housing of the transmission. TPS = throttle position sensor, this adjusts the shift points & also sets the pressure within the transmission.

[Simon Jones]

I don't recall if this was 2 or 4 WD but this is what the gearbox speed sensor looks like. The propshaft bolts onto the flange on the left of the photo:

[Alacrity]

That pic is, I believe, a 4WD unit OSS. I doub't there is a speed sensor issue as it is changing 1-2-3, but it is a simple &, I would think cheap, thing to change.

[AndyMoule]

Hi All,

I would really appreciate a bit more advice regarding this issue.

Update: I have done an oil change including fuel, air & oil filter as they were due. As predicted, this has not made a difference.

I have cleaned the banjo filter as best i could - I was unable to remove the filter with either a cotton bud or magnetic screw driver. It appears to be stuck - is this a problem?

I have checked the TPS but am not really sure what I am checking for. It appears to be properly connected but what should I do to check the TPS?

I am still not able to locate the engine speed sensor. Any tips on how to get to it? Do I have to remove anything?

The gearbox oil looks clear & red so have not done a gearbox oil change as yet.

I have purchased a new gasket & gearbox solenoid ready to change if required. What further things do I need to check before changing the solenoid?

When digging around looking for the fan switch, I found this stray tube that looks like it comes from the gear box but doesn't attach to anything. Any ideas what it is for & whether it should be attached to something?



Likewise, I have also found these electric cables floating around unattached. I guess they are from the rear speakers as they stopped working after the garage changed the cylinder head. Is anyone able to conform from these pictures?



Thank you again for all your help and apologies for the low level of understanding. This is the first time I have ever had to work on a car myself & am only doing it due to several bad experiences with the mechanics in Australia. I am enjoying it though - although it can be bloody frustrating.

Cheers

Andy