90-92 Cruise Control Fix

Joined
May 14, 2014
Messages
10
Location
NC
Hello all, i've been reading here for years but this is my first post. I've got a 90 HDJ81 with cruise control problems. Mr. Toyota no longer makes the speed sensor for the 91-92 80 series (or 90-92 HDJ81) and call me a soft but having the CC is awesome for driving our rigs long distance. I purchased a Dakota Digital GPS-50-2 GPS speed output unit (http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=837/category_id=403/mode=prod/prd837.htm)to give the factory cruise computer its speed signal and it is working great! Here is the wiring instructions:

  1. Cut four 4 inch wires (18-16 gauge)
  2. Locate your factory cruise computer (its under the dash to the right of the go pedal and just above it, in my case of an HDJ81)
  3. Unplug the wire harness and orient according to the pics included
  4. Connect pin 1 from the factory side to the 'BATTERY' label on the GPS-50-2
  5. Connect pin 14 from factory side to 'ACC PWR' on GPS-50-2
  6. Connect pin 13 from factory side to 'GROUND' on GPS-50-2
  7. Connect pin 20 from factory side to 'CRUISE' on GPS-50-2

For all connections (EXCEPT PIN 20-SPEED INPUT) I used inline wire couplers available at any auto parts store. For pin 20, cut and use a barrel connector to insert a 4 inch wire. The reason to cut is that if you still have the factory speed sensor installed you do not want any sig from making its way up the line.

You need to securely mount the GPS-50-2 as it has internal accelerometers to buffer the fluid GPS input signal. It does not matter the orientation of mount as long as it cannot move much. I used industrial velcro to mount it to the factory cruise control module (ref pics).

Ensure you purchase the external GPS antenna and secure the antenna to the dash (as you will need the best GPS signal possible)

After you have wired everything you will need to start you truck...at that point your GPS-50-2 module will go into 'learn' mode to learn which direction it is mounted and to cal the accelerometer. You need to drive in a straight line accelerate and decelerate for 2.5 sec and very your speed by 10MPH (ref the manual that comes with the unit)

After your call you will need to ensure the GPS unit is sending a 4k pulse per mile sig. Ensure truck is 'off', hold the button on the top left of the display while turning the key to ACC and then release the button. You should see -C- on display, push button until u see '-SPd' press and hold until '-' is displayed, the display should show '4' press and hold until '-' is displayed and turn key off. All of these should be default but want to include in the write up just incase.

Drive truck and enjoy your cruise again! Keep in mind the input from the system is GPS so if your driving under a thick canopy (tunnel, etc.) and loose GPS sig, you will loose reliable speed input. Also the factory cruise computer will shut down if the speed sensor input does not update within 1 sec or so. So in saying that ensure that your speed is stable on the highway before setting the cruise.
 
Joined
Apr 5, 2014
Messages
36
Hey - This is a really cool solution to a common problem. I found a less feature filled GPS unit that may work as well for a little less money. I haven't tried it yet.

JEGs GPS - http://www.jegs.com/i/JEGS+Performance+Products/555/41612/10002/-1

I may give this a shot or try to see if it possible to convert an old handheld GPS for this purpose. I have an old Garmin somewhere...

Did you ever consider replacing the hall sensor in the original? Your solution might be easier for the less electronic repair capable.

cruise control trouble - see middle of the first page for Hall sensor infor
 
Joined
May 14, 2014
Messages
10
Location
NC
Hey - This is a really cool solution to a common problem. I found a less feature filled GPS unit that may work as well for a little less money. I haven't tried it yet.

JEGs GPS - http://www.jegs.com/i/JEGS+Performance+Products/555/41612/10002/-1

I may give this a shot or try to see if it possible to convert an old handheld GPS for this purpose. I have an old Garmin somewhere...

Did you ever consider replacing the hall sensor in the original? Your solution might be easier for the less electronic repair capable.

cruise control trouble - see middle of the first page for Hall sensor infor
The speed sensor on the early 90-92 is a reed type sensor and not a hall sensor as used in the newer ones. The 93 on used a hall sensor and was all electronic to the speedometer and cruise. The early 90-92 speedometer is mechanical so the sensor has a pass through but you can't buy the sensor anymore otherwise I would have gone that route.

Yes there are a few other GPS speed sendors out there. You will want to ensure it does a 4K pulse per mile and that is has accelerometer to smooth out the sometimes not so stable GPS output
 
Joined
Jul 23, 2013
Messages
434
Location
Salt Lake City, UT
I replaced my 1992 factory sensor with a Texas Instruments hall effect sensor, works great. Cost $1.

The speed sensor on the early 90-92 is a reed type sensor and not a hall sensor as used in the newer ones. The 93 on used a hall sensor and was all electronic to the speedometer and cruise. The early 90-92 speedometer is mechanical so the sensor has a pass through but you can't buy the senso
 
Joined
Jul 23, 2013
Messages
434
Location
Salt Lake City, UT
I used the original VSS housing. There is some additional detail on this thread: Cruise Control Trouble, the mechanical speedo cable passes through the VSS and turns a shaft with a magnet. The wires on the VSS feed into a small area behind the cover. Inside is a pretty old school hall effect sensor that usually goes bad. You can remove that whole plastic mess and install a new HE sensor in its place (just make sure you waterproof/seal the cavity). Solid work on finding a different solution, but I did want to clarify that the 91/92 does use a HE sensor for the cruise control. You said you had a 1990 HDJ81 which is possible has a different setup, but I would be surprised since most of the vehicle base is the same.
 
Joined
May 14, 2014
Messages
10
Location
NC
I used the original VSS housing. There is some additional detail on this thread: Cruise Control Trouble, the mechanical speedo cable passes through the VSS and turns a shaft with a magnet. The wires on the VSS feed into a small area behind the cover. Inside is a pretty old school hall effect sensor that usually goes bad. You can remove that whole plastic mess and install a new HE sensor in its place (just make sure you waterproof/seal the cavity). Solid work on finding a different solution, but I did want to clarify that the 91/92 does use a HE sensor for the cruise control. You said you had a 1990 HDJ81 which is possible has a different setup, but I would be surprised since most of the vehicle base is the same.
Oh man!! I wish I would have found that thread before spending all that money and over thinking it all. Oh well live and learn! Thanks for the clarification on the Hall effect. Yes I think they r the same sensor. The part number leads to the same and it looks just like yours in the pic. I'll have to give that a try. I have an extra one I got from a junk yard so maybe I'll try and 'fix' that one. Thanks for the info!
 
Top Bottom