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Topic: speed sensor (Read 1258 times) previous topic - next topic

speed sensor

I am having trouble getting my speedo working again.  I haven't had it working since I swapped in the 5.0 HO and the t-5 tranny.  I broke the speed sensor in the original AOD transmission upon removal of the old engine so I tried just hooking up the mustang speed sensor no luck, so I bought a new one, no luck.  Then I took the upper portion of the original t-bird AOD sensor and swapped it into the lower shaft portion from the mustang sensor  but that didn't work either.  I have used the plastic gear from the mustang each time I put a sensor in.  Occasional I will see the speedo go up to like 2 or 3 mph and a tenth of a mile will register on the odometer but thats it.  What could cause the digital speedo to not get a signal?  How can I troubleshoot this issue?  As far as I know I have not touched any of the wires going to the sensor.  I checked them from the grommet to the sensor and the wires looked good.  Any help would be much appreciated.  I am taking the car out of town next weekend and would like to know how fast I am going.  Thanks, Jason.

speedometer

Reply #1 –
Something weird I noticed today is that the speedometer only registers while make moderate to hard stops.  I tested this theory today and did several hard stops and got it to register 4 mph while doing the braking.  After which it just returns to 0 mph and stays there.  I can't figure out if its in the tranny or something electrical.  Has anyone ever had anything like this happen before?

speed sensor

Reply #2 –
Sounds like a wire chaffing on something to me...
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

speed sensor

Reply #3 –
Is the harness to the speed sensor O.K?Perhaps you need one from a 5 speed car?Just a thought.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..
 

speed sensor

Reply #4 –
Well, I didn't see any different wiring diagrams called out in the EVTM for the 85 T-bird for the speed sensor.  That leads me to believe that the manual tranny doesn't matter.  How do I check to see if there is a good circuit at the plug?  Thanks, Jason.