ABS and brake light go on and off

doubledls

Active member
Joined
Jun 30, 2002
Location
jackson county, michigan
TDI
Jetta, 1999.5 A4, black, 2009 Jetta 6 M, black
I have been having this issue with my 1999.5 Jetta TDI: The ABS light will come on, and then go off, and then come back on again. This has been going on for almost 2 years.
In the beginning it would just happen when it was cold or damp overnight when I left the car outside, once the car got warmed up everything was OK, except that in the winter it would happen every morning, but if I drove it to work and restarted it, the ABS light would go out. In fact, I found out that if I drove for about 15 minutes and shut the car off and restarted it the ABS light would go out. Now I also get a flashing brake light with ABS light in the morning, and if I stop and restart, the flashing brake light clears but the ABS light stays on most of the time, however, yesterday when I stopped and restarted everything cleared ( I was driving up to Portland, MI) and no ABS or brakes lights were on for the rest of the trip up. However, when I started the car this morning they were back on again.
It seems when the car is warmed up that I can restart and clear these lights. I have checked the fuses and connections and they all seem good, I have also looked at the ABS sensors (they look OK), but I did not test them. The ABS works when there are no warning lights on, it does not work when the ABS light is on. The brake fluid level is also OK. This started as an occasional problem, but now it occurs every morning. Any ideas on this? The car has 301,700 miles now.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2007 Seat Alhambra 2L tdi
You could try unplugging the abs pump and reseating the plug, that can cure odd things. Also I'd be checking the earth points, not sure where they are on that car. On the mk4 there's 3 or so points under the battery tray that can cause abs light issues, maf issues etc
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
What does the scan say?
I've had several pumps exhibit similar problems till they finally stopped working.
I found that as the pumps got older the main electrical power connections to the pumps had cold solder joints.
There is a vortex thread on how to take off the computer off the abs module and cut it open.
Every pump that had an issue this was the problem. I resoldered it and now no issues.
You can find a spare abs pump and swap it out, it's a good time to do the asr mod on the car, just make sure you have VCDS to properly bleed the module.
At least this was my issue.
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagen, 2021 Atlas,2003 Jetta 261K Sold but not forgotten
My light goes on & off as well.

A scan indicated the left rear wheel sensor was bad.
Checked it, no continuity.

For 2 years (or more) the light will be on for a few months then off for a bit.

I have the new sensor, just have to install it.
 
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