89 k2500 speedo

[hammertime371]

has anyone had trouble with the speedo stop working on an 89 k2500. occasionaly it just stops working while driving. I notice it because the tranny unlocks the converter. a simple smack of the dash board and it starts working again. it has done this for years. ive taken the cluster out and checked for bad connections and such but no luck. it must be a problem in the guage itself. any ideas?

[black dawg]

It is weird that smacking the dash gets it to work again. In that body style, the ecm would get vss before it goes to the cluster right??

[EagleMark]

IIRC that truck would have turbo 400 or 700R4 and a VSS still behind speedo, now if it were 4L60E or 80E then VSS would be in trans and differant ECM/PCM. Actually I don't think the E trans was even out then... but was in later years of that body style.

[hammertime371]

its a 700r4. the vss is on the transfer case i believe. its a 4x4. but even so if it was vss how would smacking the dash make it work again?

[EagleMark]

Fear?

If the VSS is not back there then I'd say a wiring issue, but would really look gfor the DRAC. This is where the VSS signal is sent and adjusted for outputs to Speedo if Electronic, CC, ABS etc...

[jameslleary]

E trannys didnt show up in trucks till late 93.
smacking the dash like something came loose. I would take out the VSS and gander at that too, just for the heck of it.

[hammertime371]

sup guys...its been a while since i viewed this thread...never did figure it out in fact a smack on the dash still does the trick...anyway can any one say where the vssb or drac would be located... I ask because im in the middle of another tbi swap in my s-10 and i junked the donor truck befor getting the vssb out... so now im gonna need 1 to hook up the vss to the ecm and speedo... the donor vehicle was an 89 k1500... I can goto a junk yard and get 1 just want to know where it would be in the vehicle

[Fast355]

sup guys...its been a while since i viewed this thread...never did figure it out in fact a smack on the dash still does the trick...anyway can any one say where the vssb or drac would be located... I ask because im in the middle of another tbi swap in my s-10 and i junked the donor truck befor getting the vssb out... so now im gonna need 1 to hook up the vss to the ecm and speedo... the donor vehicle was an 89 k1500... I can goto a junk yard and get 1 just want to know where it would be in the vehicle

The easiest one to grab would probably be from a fullsize G-Van. They are on the brake pedal bracket or parking brake bracket depending on the year. The trucks are usually behind the cluster in the upper dash area.

[brian617]

88-89 C/K1500 DRAC is integrated into speedo cluster. 90-up they are right behind the glove box insert.

[hammertime371]

ok great info guys thanks!!

[hammertime371]

what would be the better way to go since the gear ratio and tire size is not going to be stock so recalibrating will be nessary...so should I get the vssb from the 90 and up and do the dip switch mod or is there a better way to get this done??

[buddrow]

88-89 C/K1500 DRAC is integrated into speedo cluster. 90-up they are right behind the glove box insert.

FYI, the DRAC didnt appear until either late 90 or 91 model years. My 90 is all in the cluster, no DRAC. Possibly a bad solder joint or loose wire.

Buddrow

[EagleMark]

Long ago there were some parts available from GM to slide into dash cluster and adjust speed, there's some pistures and copies of GM papers on it here somewhere... not that the parts are available anymore but might give info to adjust, like you do with DRAC/VSSB.

[buddrow]

Ya Ive had mine apart and it looks like there are jumpers just like the DRACs have, just figuring out which ones to change. The instrument connector at the dash are different on the earl trucks compared to the normal GM type connectors as well. Could be poor connection there or as was stated earlier a bad solder joint since the dash smacking has an effect on operation. :) Although I have seen the wires(insulation) at the VSS connector that degrade overtime and cause erratic VSS signal as well.

Buddrow

edit:

You should verify the cluster connector on the harness to whatever year you replace it with. As I mentioned my 90 has the early style connector and is different from the 92 I know for sure but dont have a 91 available to look at.