V70 XC, operates normal in reverse, accelerates slowly at first in 1 Topic is solved

[scot850]

I had a V70 that I purchased as a project and it had a bunch of trans errors showing. I was out of my depth so called in my friends at local Volvo dealer. I was having TCU read issues. They removed the TCU and ECU and found contact corrosion. They cleaned the units and lower contact carefully with contact cleaner and then re-fitted and removed the units 3 or 4 times to make sure the contacts were clean and good, They then cleared the codes and all was good and has been with new owner for 4 years.

As the car was sitting it is possible this may be an issue, but stressed or broken wires are just as likely as Misha says in the area of impact and any lengths of wires in that area.

Neil.

[Rocket999]

I had a V70 that I purchased as a project and it had a bunch of trans errors showing. I was out of my depth so called in my friends at local Volvo dealer. I was having TCU read issues. They removed the TCU and ECU and found contact corrosion. They cleaned the units and lower contact carefully with contact cleaner and then re-fitted and removed the units 3 or 4 times to make sure the contacts were clean and good, They then cleared the codes and all was good and has been with new owner for 4 years.

As the car was sitting it is possible this may be an issue, but stressed or broken wires are just as likely as Misha says in the area of impact and any lengths of wires in that area.

Neil.

Thanks a ton Neil that is very helpful. As a volvo greenhorn Im kinda over my head, these "computer" cars are not my prior experience.

[scot850]

Designed to drive you mad!! I spend way more time figuring out electrical issues than mechanical. so I fully understand your position!

Difference is I can usually see or hear mechanical issues but the gosh darn 'electricery' stuff where you can't see the stuff makes it harder to figure out.......!

Good Luck!

Neil.

[Rocket999]

I had a V70 that I purchased as a project and it had a bunch of trans errors showing. I was out of my depth so called in my friends at local Volvo dealer. I was having TCU read issues. They removed the TCU and ECU and found contact corrosion. They cleaned the units and lower contact carefully with contact cleaner and then re-fitted and removed the units 3 or 4 times to make sure the contacts were clean and good, They then cleared the codes and all was good and has been with new owner for 4 years.

As the car was sitting it is possible this may be an issue, but stressed or broken wires are just as likely as Misha says in the area of impact and any lengths of wires in that area.

Neil.

I tried round 1 , out and in of ECU and TCU , using ether based electrical contact cleaner on both the male and female side. Did not correct. Regarding out and in several times, would operating the removal tool back and forth a few times, which pulls those fragile looking tiny pins off and puts them back into the tiny female side make sense?

[scot850]

The reason they did that was to ensure any oxide was cleaned off. If you were worried about that then don't do it. Just give then a good clean.

You would have to clear the codes of course.

Neil.

[Rocket999]

The reason they did that was to ensure any oxide was cleaned off. If you were worried about that then don't do it. Just give then a good clean.

You would have to clear the codes of course.

Neil.

I did not see any oxide on male contacts.
Not really worried, the alignment pegs keep delicate pins aligned well and gentle careful tool use it should be safe , swedes are good at precision design. ..... simplicity? .. not so much.

[scot850]

If that does not fix it then you are probably down to damaged wiring or connection, or maybe the TCU and housing are bad. Have you been able to connect to the TCU with the diagnostics testing?

Neil.

[Rocket999]

If that does not fix it then you are probably down to damaged wiring or connection, or maybe the TCU and housing are bad. Have you been able to connect to the TCU with the diagnostics testing?

Neil.

I do not have vida dice,
the visitor guy had a bit of trouble getting his device to read it, I'm not certain how complete his result was, 1631 only
I was not going to push, he was reading it as a favor
I'm studying the elect. schematics for the wires up front most likely to take a hit in the impact

[scot850]

The main harness runs under the front RH corner of the radiator and at a slight angle across the engine bay toward the front of the transmission. The ETM wiring is also part of this harness. It is inside a plastic housing so may be a challenge to see fully.

Neil.

[Rocket999]

the schematics require time to digest and figure out due it tremendous complexity

Fun??

Swedes ... high on precision, low on simplicity.