jmel

Hello everyone. I recently got rid of a ford f150 and traded it outright for a 1990 G20 conversion van.

The ford was about the same age, and I had fixed a ton of little things on it before I realized I really wanted a van more than a truck.

On my todo list are: A/C, VSS/speedo issue, brake job, window regulator, rear power lock actuator. All of these issues existed before I got the van. I like fixing things.

I have a code 24 error, and the speedo/odometer are not working. I have replaced the VSS sensor, and even cut the wire and soldered a new one on (after matching polarity of course). I realized today that the sensor cable goes to the firewall near the battery (which was recently replaced). I was thinking of doing some basic continuity tests first to make sure there are no breaks in the wires.

Then, I was thinking of putting the voltmeter into AC mode and checking the readings at the firewall and again at the VSS buffer to see if there is any signal or any difference in voltage read.

Does anyone have any other ideas I should try? I pull the gage cluster and felt tension on the speedo needle when the van is started up. I feel like the motor is probably good in the gage cluster because of this... but since I am getting error 24, I figured that the ECM isn't getting anything from the sensor, so of course I won't get output to the gages.

Thoughts?

jmel

I've tested ac voltage and found it to be present on the sensor when the vehicle is moving. I am replacing the vss buffer today to see if this helps. I didn't get much voltage when I ran through step of this test, but there was a small amount present... :

Speedometer Inoperative

1. Unplug Vehicle Speed Sensor (VSS) buffer. On Commercial Van, VSS buffer is located on shipping panel, to left of steering column. On Van, VSS buffer is located on parking brake bracket. Turn ignition on. Check for battery voltage between Pink/Black or Pink/White wire and ground. If battery voltage does not exist, check for open or short in Pink/Black wire or Pink/White wire.

2. If battery voltage exists, check for voltage between Pink/Black or Pink/White and Black/White or Black wires. If battery voltage does not exist, check for open or short in Black/White or Black wire. If voltage is okay, raise and support vehicle. Leave VSS buffer unconnected. Start engine. Shift transmission into gear.

3. Check for AC voltage that varies with engine RPM between Purple/White and Light Green/Black wires of VSS buffer connector. If AC voltage does not exist, check for open in Purple/White or Light Green/Black wires. If wires are okay, replace vehicle speed sensor. If AC voltage exists, go to next step.

4. Check for AC voltage that varies with engine RPM between Light Green/Black and White wires. If voltage does not exist, replace vehicle speed buffer. If voltage exists, go to next step.

5. Turn ignition off. Reconnect VSS. Start engine. Put transmission into gear. Backprobe VSS connector. Check for AC voltage that varies with engine RPM between Yellow and Black/White wires. If voltage changes with RPM, replace VSS buffer.


I also found that after I had worked on it for a bit, that the speedo worked momentarily; I went down the road and it 'jumped' up to 10 mph, then tracked speed accurately for about a half mile before it quit again. I'm on to something, just don't know the root cause yet.

jmel

Well, the vss buffer fixed the problem. The speedometer sprang back to life. One thing to remember if you buy a dip switched modded buffer, is that the first pin is already jumpered.

Got my window motor and regulator done as well as the rear door actuator. Just hoping for AC soon... It's still quite hot out.