Steps in diagnosing speedometer?
#1
Junior Member
Thread Starter
Join Date: Jul 2017
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1988 camaro iroc z
Engine: 305
Transmission: 700r4
Steps in diagnosing speedometer?
I have a tpi 305 1988 and the speedometer and odometer do not work. Does anyone know steps or anything to narrow down the cause? Once I get the cluster out I can lube the cable but is there a way to tell if it's a cable, speedometer head, vss, issue? Thanks in advance, these forums have saved me tons so far.
#3
Junior Member
Thread Starter
Join Date: Jul 2017
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1988 camaro iroc z
Engine: 305
Transmission: 700r4
Re: Steps in diagnosing speedometer?
And I'm going to guess that since my Speedo doesn't work and scan tool shows 0mph at any speed, that is why my cruise control probably doesn't work.
#4
Supreme Member
iTrader: (1)
Join Date: Feb 2017
Location: Meriden, CT 06450
Posts: 4,030
Received 511 Likes
on
428 Posts
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Steps in diagnosing speedometer?
I believe yours has an electronic speedo. Look at the driver's side tailshaft of the transmission to confirm.
#5
Moderator
iTrader: (5)
Re: Steps in diagnosing speedometer?
BTW, Shakenblake, if you wish to add your car's details (car, engine, trans, etc,), go to User CP at the top left of the page, click it, then click edit details and you can update as you see fit.
Best of luck with your issues,
JamesC
Last edited by JamesC; 08-06-2017 at 09:40 PM.
#6
Junior Member
Thread Starter
Join Date: Jul 2017
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1988 camaro iroc z
Engine: 305
Transmission: 700r4
Re: Steps in diagnosing speedometer?
I forget some times this isn't a camaro only forum thanks for the info it is a camaro
#7
Supreme Member
iTrader: (1)
Join Date: Feb 2017
Location: Meriden, CT 06450
Posts: 4,030
Received 511 Likes
on
428 Posts
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Steps in diagnosing speedometer?
Does anyone know what models, Camaro and Firebird, came with a mechanical 140/145 mph speedometer?
Or was it an export only option?
Or was it an export only option?
Trending Topics
#8
Moderator
iTrader: (5)
Re: Steps in diagnosing speedometer?
1985: All 85 mph
1986: 85 mph on all Camaros, except late year Z28s with TPI, which had 145 mph
1987: 145 mph on Z28s/IROCS with TPI, both 305s and 350s
1988/89: 145 mph on IROCs with TPI, both 305s and 350s
I'm not a Pontiac kinda guy, so I could easily be wrong, but I don't believe 'Birds were equipped with mechanically driven 140s.
JamesC
1986: 85 mph on all Camaros, except late year Z28s with TPI, which had 145 mph
1987: 145 mph on Z28s/IROCS with TPI, both 305s and 350s
1988/89: 145 mph on IROCs with TPI, both 305s and 350s
I'm not a Pontiac kinda guy, so I could easily be wrong, but I don't believe 'Birds were equipped with mechanically driven 140s.
JamesC
#9
Supreme Member
iTrader: (1)
Join Date: Feb 2017
Location: Meriden, CT 06450
Posts: 4,030
Received 511 Likes
on
428 Posts
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Steps in diagnosing speedometer?
The reason I asked is because I picked to a 140/145 mechanical speedometer off of ebay for my 84 Trans Am. Brand new in the box. It was listed as for export cars.
#10
Junior Member
Thread Starter
Join Date: Jul 2017
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1988 camaro iroc z
Engine: 305
Transmission: 700r4
Re: Steps in diagnosing speedometer?
I got the new cable in after making sure driven gear was in good shape. (All stock 700r4 305 like 110ish mph speed) anyways after installing new cable the guage and cruise works!!!!!! But at like 8mph I'm readin 11mph on the guage and at 30mph im reading 40 and at 40 im reading 50. My tripometer didn't seems to start working but oh well. Scan tool confirms the pcm getting the inaccurate info. So I did re lube cable. I'm guessing my issue is in my speedo head? Thoughts, fixes?
#11
Supreme Member
iTrader: (1)
Join Date: Sep 2005
Posts: 26,051
Received 1,672 Likes
on
1,269 Posts
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Steps in diagnosing speedometer?
Sounds like you have the wrong speedo gears in it... something like, your rear end has 3.42s in it but you have the speedo gears for 2.73s. Nothing real complicated.
The fix is, install the right speedo gears to match your rear end ratio.
I think the Firebirds had mech speedo 84-back and electronic 85-up, but don't take my word for it.
It was against the law for a speedo in the US to indicate above 85 mph in a car for sale to the general public, for many years from the early 70s to the mid 80s. It was part of the national 55 mph speed limit. Hence the "export" and "police" versions that went to 140 or the like. The law was repealed sometime in 85 if memory serves.
The fix is, install the right speedo gears to match your rear end ratio.
I think the Firebirds had mech speedo 84-back and electronic 85-up, but don't take my word for it.
It was against the law for a speedo in the US to indicate above 85 mph in a car for sale to the general public, for many years from the early 70s to the mid 80s. It was part of the national 55 mph speed limit. Hence the "export" and "police" versions that went to 140 or the like. The law was repealed sometime in 85 if memory serves.