Serial no. - L90CV63088 I'm a retard when it comes to electrical. Appreciate any help, thanks. I replaced the micro switches on the shifter a few months ago and that helped for awhile but now the fuse 29 ( gear shifting ) blows every time I put it in reverse. I checked resistance on wire 177 ( gr/w ) from shifter harness to the G connector pin 9 on circuit board and get .03 resistance. When I checked resistance from G connector pin 9 to fuse holder 29 I get 73.3. I'm not sure if this is the right way to check this issue. If I'm correct is the mother board the problem or am I barking up the wrong tree. Thanks
Here are some pics.
Have you checked R11 relay? you need to have checked wire 177 (gn/w) to earth to make sure you don't have a bare wire or short to ground, then my next suspect would be the relay R11
Remove connector T from the circuit board. Back probing measure each solenoid resistance. For example T15 against T16 would give resistance for S2. Do this for all solenoids. Target value should be ~22ohms. Then measure every wire against ground. They shoul all be open since your T connector is disconnected. If memory serves S2 is reverse. All others are combinations to achieve this gear or that. If you find a dead short to black(ground wire) you'll have a better chance of finding it. Good luck
Thanks sfrs4 and funwithfuel. I'll report when done.
Relay 11 checked out OK. When I measured T15 to T16 I got 82.1 ohms. Same result from T15 to the rest. Just to be clear what I did was put one probe in T15 and the other in T16 to get the result. I'm not sure on the wires to ground check. I grounded neg to the cab frame and pos to each wire and got nothing. I also tried the neg to pin T23 ( black wire ) and pos to the rest and got 42.1 ohms. Is the black wire a ground? If I did something wrong here please correct me, thanks.
T23, black wire is ground. T14-T18 are feeds to each solenoid. You were reading combined resistance of 2 solenoids through a common ground. So 42 ohms is not unreasonable. The problem is 15-16 should have been the same as all the other. Next time let's clip ground lead to T23. Measure resistance to pins 14-18. Each individual circuit should yield about 20 ohms each. Again, Confirm that you have no continuity to chassis ground from any lead on the T connector.
Right On! Thanks for explaining funwithfuel. I'll try and get to it in the morning. The weather sucks here today and tomorrow ( snow ). Fingers get cold working outside on equipment.
funwithfuel. I have my friend the electrician helping me confirm readings. We have 41.8 ohms on each selenoid grounding back to T-23. No continuity to ground on any leads. We are checking wires to shifter.
Did you cross check each solenoid against the other? Further, since you have an electrician with you, disconnect EX connector and ask them to check the diodes on the circuit board Di 2.5 through Di 2.9 shown on the schematic. Let's make sure we don't have a direct ground via failed diode.
Don't forget Di 10 through 13. Those are from the lever carrier FnR switch
Live feed here. Diodes check out good. Selinoids against each other come up 84-85 ohms consistently.
Well damn!
Wait a minute, do you have the blue bypass harness installed as shown in the schematic you posted?
Theres a harness EX EY . Every wire should be blue. It's a harness made specifically to bypass the ECU to give manual control of the trans from the gear selector.
We left connector T unhooked which took out the selinoids in the equation and tried shifter again with new fuse power on. She blew…..good news. Pulled off shifter again and took apart. We believe there was some arching going on in there. Fix it up with some black electrical tape to keep it from arching and tried it…… working. We will see if it lasts. Thanks funwithfuel for your help. Much appreciated.
Here’s a pic of the inside of the shifter. With some time it can be fixed.
Way more patience than I'll ever have.
Considering my skills with sauldering the first time around I should have checked there first. It’s the little details that always get he best of me. It’s all good though. Learning lots on the fly here.
Is it not worth replacing the shifter? for the sake of around $320 Canadian, it's possibly a lot less hassle in the long term.... I suppose it depends on how much you use/relay on the machine, if it's just a hobby machine I can see why you wouldn't bother.
sfrs4. Good point. Machine does not get used to often. Trying to be a little more self sufficient and depend less on the Chinese imports.
Sorry, what Chinese imports?
From what I see on the internet for those shifters they come from China. I haven’t priced the shifter out at the Volvo dealer here in Canada. Anytime I have priced anything from dealer it was really expensive. I can fix it for a little bit of money. I’m also learning some basics on how these things work which is a benefit.
ahhh I see, the idea is good in practice and it's nice to see people trying to fix and recycle not just buy new. I'm not going to go into all the details, but be aware an awful lot of components are made in china now and I mean components fitted in the factory, so what you are seeing is OEM and at the correct price not manufacturer inflated prices.