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If L2 live at neutral when second gear needs 12v power for shifting hydraulically and electronically but power lives at neutral that time then shifting going on by speed sensor electronically only but not hydraulically by shift solenoid. Is that make sense ?
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L2 does not power anything in the valve body. When the ignition is on, the solenoids receive continuous live and are activated when grounded by the TCM. The function of L1-L4 is to tell the TCM which gear is selected.Originally Posted by Annddrriy
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Should L2 terminal power with at least 10 volts at pin 28 of TCU when ignition is ON and gear selector is set to position 2 ?
Last edited by Annddrriy; 05-25-2022 at 01:11 PM. Reason: Terminal L2
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Should pin 31 of TCU power with 12v L2 terminal when ignition is ON and gear selector is set to position 2 ?
Last edited by Annddrriy; 05-25-2022 at 01:13 PM. Reason: Terminal L2
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Power to switches L1-L4 comes from fuse 17, not pin 31 of the TCM. With the ignition on and the gear lever in manual 2, L1 will provide power to TCM pin 18.
Last edited by whiskychaser; 05-27-2022 at 09:03 AM.
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How to understand E-7 Early version TCU pin 31 has power 12v and E-7 Late version hasn't power ?
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How to make it missing copper road track in Range Selector Switch to get powered with 12v L2 terminal ?
Last edited by Annddrriy; 05-25-2022 at 03:05 PM. Reason: L2 terminal
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If you have not got the appropriate diagrams, you are going to have to find out if that is an input to or output from pin 31. Then trace the wiring
If it is so badly damaged that copper track is missing, the switch needs to be replaced.
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What do you think from your perspective power should go to TCU pin 31 or should coming out from TCU pin 31 ? Thanks in advance !
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BMW and Bentley wiring diagrams do not show pin 31 of the TCM being used until 1991 when it is grounded by the brake light switch.
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I mistaken with pin number that is 28 pin. Should pin 28 of TCU power with 12v L2 terminal when ignition is ON and gear selector is set to position 2 or power should coming out from TCU pin 28 and power L2 terminal 3 at selector position to second gear ?
Last edited by Annddrriy; 05-26-2022 at 05:12 PM. Reason: Pin 28 power L2 or L2 power pin 28
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Pin 28 is an input, not an output. It works as I mentioned above
Last edited by whiskychaser; 05-27-2022 at 09:04 AM.
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Yes my mistake. One wire from fuse connect to all 4 terminals L1L2L3L4. L2 is terminal 3 at selector position switch which is not getting 12v power when gear selector is set to position 2 that is E-7 Early version but in Late version shows not powered which diagram should be correct ?
Last edited by Annddrriy; 05-26-2022 at 08:24 PM. Reason: E-7 Early version L2 terminal is powered at gear selector in position 2 and in E-7 Late version is not powered.
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Power to switches L1-L4 comes from fuse 17 with the ignition on and the gear lever in manual 2, L2 will provide power to TCM pin 28 if L2 will not provide power to TCM pin 28 what will happen then ?
Last edited by Annddrriy; 05-26-2022 at 08:29 PM. Reason: L2 provide power to TCM pin 28
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The shift matrix is the same from 1987 through 1992. The diagrams confirm it. If you have got hold of a switch from a N American E34 with an A4S310R trans, the matrix will still be the same. But L2 will be wired to pin 26 of the TCM and not pin 28. If you are using the correct TCM for your car and there is no live to pin 18 when you select second manual, the TCM will not know which gear you are requesting and it is likely to throw TRANS PROGRAM.
Last edited by whiskychaser; 05-27-2022 at 09:18 AM.
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29 is ok with power at selector position to 3rd gear. Why TCU pin 28 need for ?
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L3, which supplies pin 29, is the only switch which is closed when manual third gear is selected. Check out the matrix table
matrix.jpg
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I am working on BMW E32 735i 1990 checking selector position switch key on engine off selector gear is set to position 2 at TCM =28 there is no 10 volts. Is selector position switch faulty ?
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OK. Now I am have made a mistake but at least I have spotted it myself.
Correction: In second manual, L1 is the only switch closed. So pin 18 of the TCM is the only one which gets a live. Check the table above and the diagram on page 2460.04
Last edited by whiskychaser; 05-27-2022 at 09:21 AM.
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Manual I have written key on engine off TCM pin 28 should has at least 10 volts when selector is set to position 2nd gear. There is no 10 volts at pin 28. Is that selector switch faulty ?
Last edited by Annddrriy; 05-27-2022 at 11:16 AM. Reason: 2nd gear TCU pin 28
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As mentioned in my post 470 above, I realised that I had also made a mistake when explaining how the system works and corrected posts accordingly. Please accept my apologies for any confusion caused
If you check the table in my post number 468 above, you will see that when second gear is engaged, only switch L1 is closed. So 12v is only switched to terminal 18 of the TCM. Terminals 28,29 and 30 remain at 0v. If the cluster shows the correct gear, the switch is unlikely to be faulty. But it is still worth checking the inputs to the TCM
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Wiring diagram shows each terminals of L lives and matrix shows L4 and L3 lives at D and 3 gears selected. When gear selector is set to position 2 matrix makes switch to L1 ?
Last edited by Annddrriy; 05-27-2022 at 08:06 PM. Reason: Matrix switch to L1 when gear selector is set to position 2
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L4 and L3 power present when selector is set to position D and 3 and when selector is set to position L2 no power at TCM pin 28. Do you know what time power go to TCU pin 28 ?
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Yes. For future reference, the diagram below contains the matrix table and wiring. You can see that L2 is connected to pin 28 of the TCM and that it is only made in P and N.
matrix2.jpg
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When gear selector in second position L2 then TCU pin 28 do not need 12v ?
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