'98 V70t5 ABS/Tracs warning light issue

[michael8888]

hello all,
I've been having the dreaded ABS/Tracs warning light issue.
Code is: 443 Pump motor, electrical or mechanical fault.

here's the issue: the abs/tracs light only stays off for 10-60 minutes and comes back on for sometimes days at a time.
On live scan while drive the car its not getting speed signal from front left wheel.
Sometimes when the warning lights are off, I'll get a pulsing sound from the ABS pump while driving. This happens when I'm NOT on the brakes. When the pulsing stops in a few seconds the warning lights go back on.

what I've tried:
first, I have replaced the ABS 2/4 wheel tracs module with rebuilt ones twice and a good ebay find. no luck
second, I replaced the front wheel sensors and even swapped them from left to right to be sure I didn't have a bad one.
third, I changed the wire to the front left abs sensor with an oem wire.

I'm not sure if I have a bad pump or there is a short I can't find. I do have a spare pump, but it such a pain to change, I'd like to hear from the group for some other options first. Like, are there relays or areas in the harness or connections seem to fail and should look at first. Would a bad valve in the pump cause the 443 code?

thanks,
M

[bmdubya1198]

You say you replaced the ABS module. Do you know that the ABS module you have in the car is the correct one? For your car, you need 1998 FWD w/ TRACS.
The 443 code can come up when the module is failing, and it's giving a bad signal. But since you say the ABS pump is running like it is, I think that may be the issue here, although the pump itself doesn't fail very often at all.
I would wait for Matty Moo to chime in, he's the ABS guy here.

[wizechatmgr]

Have you checked the harness for a short on the front left wheel? You can plug good sensors in, but if you aren't getting a signal back at the module you're still not achieving your goal. Have you also verified you're getting good pickup at the wheel? With a multimeter hooked up you should see the voltage swing as the hall effect occurs. (I'm assuming these are hall sensors - wouldn't make any sense to use anything else)

[michael8888]

the module is correct and the sensors are good. I'm not 100% sure the pump is functioning correctly all the time. The pump motor may work, but if the values in the block are stuck I believe it may cause the error code.
I'll put a multi-meter on the wire to double check its OK this week, but it was replaced a few months ago

[scot850]

Did you replace the ABS module yourself? Reason for asking is the cable harness connector is know for having issues and breaking wires. Also know for not seating correctly. I have heard of guys using wedges to make sure it stays seated correctly.

I would suggest you may want to look there rather than the other areas. Do check you have the correct ABS module as suggested, but I don't see why that would only affect mostly one wheel.

Neil.

[michael8888]

trust me it's the correct module and harness is seated correctly. the first 2 modules were from a module rebuilder my friend who owns a volvo repair shop got for me on exchange for my original. the third was from ebay. all have the same mod # as the original.
It doesn't seem to be a cable to harness connection issue. I too have read about people using the wedges and tried that a year ago and it made no difference. I cleaned all connection points with contact cleaner and reseated using di-electric grease.

I'm going to test terminal points 4 and 11 to the front L wheel later this week and put an ohm meter to the motor.
Are there any hidden relays in the system?

[Matty Moo]

Put 12v to the pump motor AND check resistance. Don't forget you have two fuses for the system in separate boxes.

It's unlikely you have stuck valves in the pump assembly.

[michael8888]

I tested the wires from all 4 wheel sensors to where they connect to the module and got good ohm response. @ 1.1 for each
motor showed good continuity, but couldn't really test for resistance today. both fuses test OK.
I'm going to test to see that power is really leaving the fuse box and getting to module next.

[michael8888]

hey all,
I'm still working on the ABS.
I change the ignition switch last week just in case it was the culprit. The new switch helped with some other minor issues and the ABS is still going on and off, but now it put up additional new code: abs422, outlet value left rear wheel, fault in the valve coil circuit. I'm using my friends Autel Maxisys Pro MS908P which is a seriously good scanner.
It's hard to believe I've gotten 3 bad control modules. Although very rare, is it really possible the pump is bad or are the valve coils in the module and I'm the new crowned king of bad abs modules.
thanks,
m

[abscate]

I think it's probably the pump , but you are indeed in uncharted waters

Have you pulled the Volvo info on that ABS CODE?