Speedo - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Free88 · 08-11-2005, 09:31 PM

Please help. Have a 91 chevy 1500, speedo doesn't work does anyone on this forum have any ideas. Posted on 88-98 forum but no replies. Thanks.

Russell · 08-11-2005, 11:11 PM

Check to make sure that your speedo is getting power, and also check to make sure that there is something of a signal coming from your DRAC (the little yellow box somewhere nearby your ECM, it converts the 40 pulse per driveshaft revolution signal coming from your tranny into the 4 pulse per speedometer cable revolution signal that your speedometer wants)

Free88 · 08-11-2005, 11:45 PM

Thanks. WIll give it a try.

Russell · 08-12-2005, 02:40 AM

Yep, no problem!

Should be fairly easy to figure out! Those trucks speedometers only need power ground, and a VSS signal to operate

piecesparts · 08-12-2005, 08:28 PM

The early 90s vehicles had some problems with the pickup unit in the tranny failing. Once it goes the speedo will not receive information for a speed.

Russell · 08-12-2005, 08:45 PM

Your check engine light would also come on in that situation. If you do find out that your tranny sensor is the problem, gimme a PM, and I can send you a known good one from my 89's old blown 700r4 for the cost of shipping

There is always the possiblity that your check engine light may be burnt out or something.

piecesparts · 08-12-2005, 09:15 PM

Check engine light ----Not always---Had one go and the light didn't come on. My light was good also. If it is made by man, it might never work right.

08-11-2005, 09:31 PM	#1
Free88 Registered User Join Date: Jan 2004 Location: Northwestern Ontario Canada Posts: 359	Speedo Please help. Have a 91 chevy 1500, speedo doesn't work does anyone on this forum have any ideas. Posted on 88-98 forum but no replies. Thanks. __________________ 1986 Silverado Short box fleet side. project 2005 VW Tiguan 4 Motion 1997 Blazer S10 4x4 1990 Chevy Silverado K1500 Extended long box

08-11-2005, 11:11 PM	#2
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Check to make sure that your speedo is getting power, and also check to make sure that there is something of a signal coming from your DRAC (the little yellow box somewhere nearby your ECM, it converts the 40 pulse per driveshaft revolution signal coming from your tranny into the 4 pulse per speedometer cable revolution signal that your speedometer wants) __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

08-11-2005, 11:45 PM	#3
Free88 Registered User Join Date: Jan 2004 Location: Northwestern Ontario Canada Posts: 359	Thanks. WIll give it a try. __________________ 1986 Silverado Short box fleet side. project 2005 VW Tiguan 4 Motion 1997 Blazer S10 4x4 1990 Chevy Silverado K1500 Extended long box

08-12-2005, 02:40 AM	#4
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Yep, no problem! Should be fairly easy to figure out! Those trucks speedometers only need power ground, and a VSS signal to operate __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

08-12-2005, 08:45 PM	#6
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Your check engine light would also come on in that situation. If you do find out that your tranny sensor is the problem, gimme a PM, and I can send you a known good one from my 89's old blown 700r4 for the cost of shipping There is always the possiblity that your check engine light may be burnt out or something. __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

08-12-2005, 08:28 PM	#5
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	The early 90s vehicles had some problems with the pickup unit in the tranny failing. Once it goes the speedo will not receive information for a speed.

08-12-2005, 09:15 PM	#7
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Check engine light ----Not always---Had one go and the light didn't come on. My light was good also. If it is made by man, it might never work right.

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