TRACS/ABS: 70: Flashing up arrow and CEL, no ABS light

[sagedavis]

Hello--I would appreciate any expert help.

2000 S70 (standard, non-turbo)
117K miles

I had Check engine light come on with flashing up arrow; however ABS light never came on (comes on briefly at startup only). Volvo mechanic said I needed a new ABS brain, said car was starting off in 2nd gear. Codes he gave me are:

TCM 001F Vehicle speed sensor signal missing
TCM 0020 Vehicle speed faulty signal
ECM 530D DTC in transmission control module

I was not willing to pay him $700 to replace ABS, so I paid the $86 for diagnosis and promptly replaced the ABS with a used one I bought online from salvage dealer. However, the CEL and flashing up-arrow stay on, cruise control does not work and the "W" button at foot of shifter does not seem to do anything when pressed. The ABS light seems to be functioning properly, and it seems to be going through all of the gears and runs great.

Today I stopped by Autozone for a generic code read:

P0722 (ODBII- no voltage signal from output speed sensor)
P1618 (ODBII- SBDS interactive codes???)

Do I just need to buy a code reader and erase/reset the codes?

Or do I have another problem?

Thanks for any advice...
Cheers, Jim

[Chris_Rogers]

I would think this is your best option:

http://home.earthlink.net/~vicrocha/

[sagedavis]

Chris, thanks for reply.

Agreed that I am assuming my replacement ABSS unit is good--mainly because the ABS light on dash does not stay on past briefly at startup (presumabley to signal that the light bulb is working). Hence, replacement ABS I have may not be good, and I should have my original one rebuilt.

However, if that is the case wouldn't I have other issues like, ABS light on, no speedometer, others?

[Chris_Rogers]

Sorry, misread the post:

The fault is with the vehicle speed sensor on the transmission, not the ABS.

The automatic transmission control module (TCM) receives speed signals from the vehicle speed sensor (VSS) on the transmission. The transmission control module (TCM) uses the signals to select the correct gear. The control module derives and compares the transmission speed with engine speed (RPM) at the transmission. Diagnostic trouble code (DTC) TCM-0020 is stored if the control module registers that the signal from the vehicle speed sensor (VSS) is missing.

Suggest you check the wiring first and the resistance of the sensor, if not OK repair wiring/ replace sensor.

[sagedavis]

Great thanks, that makes sense to me.

I am assuming the VSS is on top of tranny and I need to take battery out first , and that the resistance should be 300-600 ohms between VSS terminals?

[Chris_Rogers]

From memory there is an input speed sensor and an output (vehicle speed) sensor, these are the same, so you could compare the resistance of each.

[sagedavis]

Just to close the loop and thank Chris for help.

Problem turned out to be a bad VSS (vehicle speed sensor), which I replaced and cleared codes...up arrow and CEL are not on know and car running great.

[simondolanbass]

Hi, I have the same problem. Is it the front or rear speed sensor?
Simon