Hi everyone,

I recently bought a tr magna EFI auto sedan and the transmission is stuck in one gear, I dont know if that is 2nd or 3rd. Does anybody know a cheap reliable place to get this fixed near Morley in Perth WA?

Hi Andrew ...
do you have reverse gear also? If you do, its more than likely your TCU (transmission control unit) which is defective. Its the small computer which looks after all things transmission-wise.
My advice would be to have it checked by someone to confirm this fault, then, if you need to purchase one, don't buy from a scrapyard, unless you absolutely have no other option.
The fault which develops in these units is (usually) a leaking capacitor and/or a burnt chip. This leakage is thought to begin after about 3 to 5 years of age. So, as you can see, buying from a wreckers is a futile exercise (unless the wrecked car has a reconditioned unit already fitted). The last one I purchased was from 'Repco'. Good luck ... Dan

Hi everyone,

I recently bought a tr magna EFI auto sedan and the transmission is stuck in one gear, I dont know if that is 2nd or 3rd. Does anybody know a cheap reliable place to get this fixed near Morley in Perth WA?


Hello andrewtp21,

First pull the fault codes from your magna for the transmission.

Pulling the fault codes ---> http://www.diamanteowners.com/forum/index.php?showtopic=64648

Removal and inspection of the TCU ---> http://www.diamanteowners.com/forum/index.php?showtopic=62534

As Dan explained, the TCU can fail just like your ECU.

TG

ill lay bets that the autos computer has fried remove the computer and then remover the cover off the top of it look for any burnt chips or bubbles on the flat black ones

What makes you guys so sure its the TCU?
The transmission will go into "limp mode" whenever it detects there is a fault. It could be anything to do with the transmission. Try and get the fault codes, if that fails try resetting the TCU by disconnecting the battery for an hour. If that fails, take it to a specialist.

Thats what we indicated TR.

Check the TCU first prior to taking it out. Changing these units is not the easiest of tasks, unless you're a contortionist, so of course its wise to check it out first. One would endeavour to do this with any electronic or mechanical component if its at all possible. Saving yourself time, energy and money is the name of the game.

These items are not cheap by any means, so verifying its demise before changing it is a very wise step indeed.

Dan.

If the transmission is locked in one gear check the fault codes. If any of the fault codes 81-86 appear there is a problem with with something else and it is probably not the TCU.

To Test

Connect the negative lead of the test equipment to pin 12 (top left) and the postive lead to pin 6 (bottom left) of the diagnostic test connector and turn ignition on. Read codes

The code can be read with a LED test light or high impedence (Min 1 megohm) analogue volt meter.

The pulses are displayed as a series of long and short pulses. To identify the the code number, note the number of long and short pulses. One long pulse followed by 4 short pulses is code 14. If more than one code exists they will be displayed in numerical order with a pause in between. If no faults are present a continuous series of short pulses will be displayed

TCU Codes

The codes marked with a * apply only to the F4A33 (EFI 4 and 6cyl) Transmission. All other codes apply to both the F4A23 and F4A33

11 Excessively high TPS sensor output
12 Excessivley low TPS sensor output
13 TPS Malfunction
14* Improperly adjusted TPS
15 Open circuit in low temp side of oil temp circuit
16* Short circuit in high temp side of oil temp circuit
17* Open circuit in high temp side or short in low temp side of oil temp circuit
21 Open circuit kickdown servo switch circuit
22 Short circuit kickdown servo switch circuit
23 Open circuit pulse pick up cable circuit
24 Open circuit or improperly adjusted accelerator switch
31* Open circuit pulse generator A
32 Open circuit pulse generator B
41 Damaged or disconnected wiring of shift control solenoid valve A system
42 Short circuit shift control solenoid valve A system
43 Damaged or disconnected wiring of shift control solenoid valve B system
44 Short circuit shift control solenoid valve B system
45 Damaged or disconnected wiring of pressure control solenoid valve system
46 Short circuit pressure control solenoid valve system
47 Damaged or disconnected wiring of lock up clutch control solenoid valve system
48 Short circuit lock up clutch control solenoid valve system
49 Malfunction of lock up clutch system
51 First gear non sychronous
52 Second gear non sychronous
53 Third gear non sychronous
54 Fourth gear non sychronous

If certain faults codes are generated four times the computer enters limp mode and displays the following fault codes. In limp mode the transmission is lock in third gear when drive is selected and locked in second gear when 2 or L are selected.

Below is the limp mode codes followed by a description followed by the code that was generated four times.

81* Open circuited pulse generator A code 31
82 open circuited pulse generator B code 32
83 Open circuit or short circuit shift control solenoid valve A code 41 or 42
84 Open circuit or short circuit shift control solenoid valve B code 43 or 44
85 Open circuit or short circuit pressure control solenoid valve code 45 or 46
86 Gear shifting does not match engine speed code 51, 52, 53, 54

tr magnas allways fry auto comps very commin i know because i spent 3 weeks locating the comp to replace it

Hello andrewtp21,

Pull the fault codes first. I would not recommend disconnecting the battery. This will clear any fault codes that the TCU has stored and the transmission will still be stuck in limp mode.

I've had my F433A tranmission go into "limp mode" for two different reasons.

One was for the pulse generators which went bad. Their attached to the transmission valve body inside the tranny. The other was the TCU was bad. The capcitators leaked and caused damage.

TG

It amazes me sometimes how many people can come up with so many reasons for a common problem.

Yes if you disconnect the battery the fault codes will clear.....HOWEVER if you disconnect the battery, clear the codes and the problem initially clears, you then can get the codes read. If the problem is present as soon as clearing the TCU memory, you can assume the TCU has shagged. If it clears and does not come back, then you are fine.

Mine has shagged itself a few days ago, looking for a cheap TCU, the symptom is stuck in third all the time when in D, 2, 1 It wil never select 2 or 1 regardless of where the shifter is.

If you have done your trans, you will have either no drive, no reverse or another obvious symptom.

BTW, I have a TS one here if any one is after one.....

i have a tr carby one here...