Chevrolet Repair: Speed sensor issues: raising the car . . ., pigtail connector, butt connector

Question

New speed sensor and c   QUESTION: Hi, Tom,

It turns out that the part I'd ordered and hoped was right wasn't -- but, fortunately, I bought the right connector yesterday locally, over the counter.

Briefly: The teacher managed to splice in the new connector (thanks for the butt-connector idea -- I bought some yesterday, and two were used).

Then, some piece of plastic, the teacher thought, was caught in the old sensor's port area, and she ran out of time and gave up trying to dislodge it -- but I managed to get it out with the end of a paper clip.

After that, I got the new connector to fit in -- no snapping sound, but it looked and felt good.

Unfortunately, after I started driving the car, the speedometer STILL didn't work -- and that's where things are now.

I don't really know what to do next.

The splicing could have been done poorly -- the teacher at one point said that one of the wires was coming loose, or something like that.  (Although I'd mentioned that I'd brought shrink tubing, she didn't use that.)

She thought maybe the old sensor was no good or that the computer had been damaged when the old pigtail connector came off.

The project continues! :)

P.S. I'll attach a photo I took of the connector I used, along with the new, unused speed sensor that seems to match the old one that is on the vehicle.

ANSWER: HI GEORGE,I WOULD THINK THAT THE CONNECTION YOU AND YOUR TEACHER MADE ARE PROBABLY OK...THIS IS VERY EASY TO DO !!! I THINK THE PROBLEM IS EITHER THE SPEED SENSOR ITSELF OR THE COMPUTER IS NOT RECIEVING THE FEED BACK INFO,,BECAUSE OF A WIRING ISSUE OR JUST A FAULTY COMPUTER. THE OTHER PROBLEM COULD BE A BAD SPEEDO HEAD IN THE DASH...YOUR NEXT MOVE WOULD BE TO GET A SPEED SENSOR AND PUT THAT IN..IF THAT DOES NOT WORK TAKE THIS CAR TO A SHOP THAT CAN HOOK THERE SCAN TOOL UP AND WATCH THE LIVE DATA TO SEE IF THE COMPUTER IS READING THE SPEED SENSOR. THIS WAY YOU WILL KNOW IF THE SPEED SENSOR AND WIRING AND COMPUTER ARE OK..IF SO THE SPEEDO ITSELF IS BAD..WHEN YOU SCAN THIS WE ARE NOT LOOKING FOR TROUBLE CODES WE ARE LOOKING AT LIVE DATA..
ONE LAST ISSUE,IF YOUR TEACHER DID NOT USE THE SHRINK TUBING I WOULD DO SO TO KEEP THIS WIRING DRY AND CLEAN...VERY IMPORTANT... I HOPE THIS HELPS YOU AND GOOD LUCK,,TOM...

---------- FOLLOW-UP ----------


Wider view of on-vehic  
Cropped view of speed-   QUESTION: Hello, Tom,

Thank you for your latest answer.

I left something at class last night, so I went back to get it today.

When there, I talked to a couple of people, including one instructor.  After showing the photo of the close-up of the speed sensor port, he said that the sensor was “cooked.”  Thus, it should, apparently, be replaced.

I’ll attach a picture of it.

I noticed – and pointed out – that there was a black area at the right side of the sensor port.  This was the same area where the teacher had noticed what she thought was plastic.  

My assumption or theory – is that (maybe) this occurred when the pigtail connector was working itself loose (by the way, that old connector only had one of the side clips, per what I saw yesterday), thus creating an arc.  

Anyway, if an arc DID occur, that would explain the (melted) plastic in that area, which, I assume, would have come from the old pigtail connector itself.

The thing to do indeed seems to be to replace the sensor, as you mentioned.

Since I have no lift on which to raise the car, though, that is a practical problem.

However, the other person at the school mentioned that I could use jack stands (which I don’t have and don’t have much room to store).  I could do that.

(A note: At first, I’d thought that it wouldn’t make sense that the speed sensor was out of order, because the speedometer seemed to be working perfectly, UNTIL, apparently, the wiring came loose – however, if the loosening of the wiring caused an arc that damaged the sensor’s ability to work, then it could explain why both the connector and the sensor would be in need of replacement.)

About the shrink tubing: I don’t know, but wouldn’t that normally be placed over the wires BEFORE they are attached together?  Otherwise, I’ll have to cut a length of it lengthwise, so that it will fit over the already spliced-together wires, isn’t that right?

Do you have any suggestions as to how long the shrink tubing should be?  I feel two inches would be long enough: Does that jibe with what you feel is the right length or minimum length?

Thanks again for your help.  If you have any feedback beyond what I’ve asked about here, please feel free to inform me of it.

(I’ll also attach a picture showing more of the sensor: It is an uncropped version of the same picture that I mentioned here that shows the enlarged view of the speed-sensor port.)

Best regards,

-- George
P.S. In looking over your reply, I noticed the live-data idea, which I'd mentioned to the teacher some time ago.  I understand that wasn't possible or at least practical for the lab because my car is OBD1, not OBD2.  However, I do like the idea, and sent her a video where someone was showing that being done in a vehicle that was in motion.  Of course, if I replace the speed sensor and the speedometer works, then that is a moot point.

ANSWER: HI GEORGE, YES YOU ARE CORRECT, THAT SPEED SENSOR IS COOKED.  AND YES YOU ARE CORRECT AGAIN, THIS IS PROBABLY WHAT HAPPENED.  THE HARNESS CLIP GOT CORRODED AND THERE WAS A LOT OF ARCING INSIDE OF THE HARNESS WHICH RUINED THE HARNESS AND SPEED SENSOR. AND YES AGAIN, YOU ARE CORRECT THAT YOU WILL NEED TO CUT THE WIRING THAT YOUR TEACHER AND YOU SPLICED TOGETHER WITHOUT PUTTING THE SHRINK TUBING OVER THE WIRE.  THIS HAS TO GO ON THE WIRES BEFORE YOU SPLICE THEM TOGETHER.  AND I LIKE TO SEE 3 INCHES BARE MINIMUM OF SHRINK TUBING, THIS WILL COVER THE BUTT CONNECTOR AND RUN UP THE WIRE TO SEAL CORRECTLY.  IT SOUNDS TO ME LIKE YOU HAVE ISOLATED THE PROBLEM AND THE CAUSE AND I THINK AFTER YOU TAKE CARE OF THIS, EVERYTHING SHOULD BE A-OK.  
AGAIN, IF YOU HAVE ANY MORE PROBLEMS WITH THIS, FEEL FREE TO GET BACK TO ME.
- TOM

---------- FOLLOW-UP ----------


Speed sensor as seen f   QUESTION: Hello, Tom,

Thanks for your latest answer.

I’d like to ask a question that I touched on but didn’t actually ask you outright:

How/where can I get my car raised up so that I can get underneath it (if that’s what I need to do, versus working from over the engine) to change the speed sensor?  I’m looking for something inexpensive, safe, and not too difficult to do.  

(Of course, I can buy jack stands – and learn how to use them, which I don’t know now – and store them in my one-bedroom apartment, but there may be a better option.)

Since I mentioned the possibility of working on it from above, I’ll attach a photo of the current speed sensor as seen from above.  (There seems to be some sort of hood over it, by the way, which I think will come off with the speed sensor itself.)

Thanks again,

-- George

Answer
HI GEORGE, I LIKE USING DRIVE UP RAMPS,BUT THEY TO TAKE UP ALOT OF ROOM...HOW ABOUT A FLOOR JACK AND BLOCKS..FOR SAFTY !!!WHEN YOU ARE DONE WITH THE BLOCKS THROW THEM AWAY..BEST WAY  I KNOW OF..I DO NOT THINK THERE IS A COVER OVER YOUR SPEED SENSOR..I THINK THIS LOOKS LIKE THE BACK SIDE OF THE EXH MANIFOLD WHICH LOOKS LIKE IT IS OVER IT BUT IS NOT.JUST REMOVE THE HOLD DOWN BOLT AND LIFT IT UP AND OUT..GOOD LUCK,,TOM...