08 xc90 lost canbus? Topic is solved

[precopster]

If you can get the fault to disappear long enough to investigate the 2 software part numbers on the TCM in Network, you can then swap in another TCM and either have it reprogrammed by Yagger OR it may well match if from the same model year and engine type.
TCMs are available at yards; could be worth a try

[2000c70hpt]

Yes I'll try that that. Though I belive it has gone beyond my level of expertise. Looks like it might be dealer bound to at least get a diagnosis. That or it's getting driven into the gulf of Mexico to never be seen from again

[precopster]

You'll need a ECM/TCM removal tool or work on the pink sliders under the computers by removing the plastic case.

First get the software numbers off the TCM before it turns into a 100% failure

[2000c70hpt]

Precopster, on my c70 I need the tool you mention, but the xc90 doesn’t. The tcm is bolted to the transmission where the pnp switch would go, and my ecm is on top the air box.

[precopster]

Not really a bonus then, those front mounted computers can have very delicate connector tabs that break off easily. I suggest pulling them when warm.

Have you tried removing TCM connectors and spraying connectors with contact cleaner? At this age and with extreme changes in climate (floods, then warm weather) some corrosion on the connectors can cause your symptoms.

[2000c70hpt]

Yes I have. The only thing I haven't done is scoped the canbus yet. But I have an idea for checking my fuel pump issue. Gonna put a volt meter on the pump side of the pem, and when the pressure drops off my voltage dies out, I'll check the ecm side of the pem to see if that's where my drop is. I'm thinking at this point the ecm is getting hot and that connection is failing.
So far I have found a common contributor. It's temp related. First run of the day perfect. Anything after that is hit and miss

[2000c70hpt]

Well just as an update. It’s going to the dealer. Spent another 3 hours today checking wires, and voltages and the only thing I have managed to do is regain fuel pressure with a pem signal voltage from the ecu @ 3.5-4 v consistently. The tcm had to be disconnected the whole time though. Nothing is shorting out, though there is a. 1v leakage from the ecu with ignition off, key out. One question though. The yellow wire appears to be a wake up signal for the modules. Does anyone know what the voltage should be at key on, engine running, and key out scenario. I’m getting battery voltage at key on for a second, then 0 zero voltage while engine running

[2000c70hpt]

Found out my dice unit cable is messed up. Went to check my c70 and no comm. sounds like I fixed my communication error with xc90 lol

[2000c70hpt]

Turns out it was not a failed fuel pump, but sediment and gravel in the tank clogging up the pump pickup. Changed the pump today and so far so good. Thank you all for chiming in and helping with this issue. So far no codes except for the stupid little light bulb in the antenna ring around the ignition switch. Next is suspension, bodywork, and a starter. What do you guys recommend for heavy things for shocks and struts? I want something a little stiffer than stock, but not sports car ride. My c70 is getting the sports car ride setup.