98 MK3 instrument cluster and warning light issues

jackgreen

Veteran Member
Joined
Nov 15, 2008
Location
lewiston, northern california
TDI
1998 jetta tdi
i have a 98 MK3 with instrument cluster and warning light issues. i was changing the fuel filter last year and did not have my mityvac handy so i ended up with excessive cranking to bleed the air out. yeah i know, dumb move but i was lazy and i did not care about this car at that time.


so here are the current symptoms. i get no vag-com communication at all, clock resets at startup, tach only works once the engine starts and shudders(the tach not the engine) when i turn it off and restart, trunk, airbag, check engine, glowplug lights are all on.



my thoughts are bad ground or bad cluster.


thoughts on where to start? ground locations? i know of two but i don't want to miss any.
 
Last edited:

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
The cluster ground is at the rear of the head, by the Orb.

I had a shuddering tach needle and it ended up being the chip. Loss of clock, sounds like the B4 issue, so that may be a cap, but I never heard A3 owners with issues.

No clue about no comm or your warning lights.

-Todd
 

jackgreen

Veteran Member
Joined
Nov 15, 2008
Location
lewiston, northern california
TDI
1998 jetta tdi
The cluster ground is at the rear of the head, by the Orb.

I had a shuddering tach needle and it ended up being the chip. Loss of clock, sounds like the B4 issue, so that may be a cap, but I never heard A3 owners with issues.

No clue about no comm or your warning lights.

-Todd

Thanks for the tips. could you clarify what you mean when you say "head" "orb" "cap" and "chip"? just want to be sure we are speaking the same language etc.
 

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
Head is cylinder head
Orb is main engine connector
Cap is capacitor
Chip is computer chip, on the cluster board

-Todd
 

Stromaluski

Veteran Member
Joined
Oct 23, 2013
Location
Greenville, SC
TDI
'67 Deluxe Bus, '80 Rabbit Truck, '92 Corrado, '10 Cup Edition
Mk3 clusters are bad about having cracked solder joints where the connectors on the back of the cluster connect to the circuit board. It will cause all sorts of weird issues. May be worth checking into as a possibility.
 
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