: Speedometer Gone Crazy



rpanzera
06-20-13, 09:24 AM
I have a 2007 DTS. The speedometer is reading erratically at various speeds. Sometimes reads moving when stopped. I replaced the vehicle speed sensor at the transmission and it corrected it for two days and now back to erratic again. Anybody got any thoughts?

Thanks in advance.

NCDTS
06-22-13, 03:39 PM
Hi rpanzera, it sounds like it’s happening frequently so I suggest you take it to a dealer so they can try to diagnose the problem when it’s happening. And if they find out what’s going on, please share.

The reason I have my DTS at the dealer (see the Speed Limit Display? thread) is to give them some time to investigate a random erratic speedometer, with occasional engine revving. I’ve never been able to duplicate my problem while I’m at the dealer or on the road with service personnel. Since the problem doesn’t throw any engine codes, and it can’t be easily duplicated, I expect it to be a hard one to solve.

I’m not sure when it first happened, but it was a wet day and I was at least 20 miles from home on the highway. The cruise kicked off, then the speedometer needed dropped down and flipped back to the correct speed, and I got a brief message in the DIC “Speed Limited to 108 MPH”. Then the speedometer would either drop and come back to the correct speed, or flip over to a higher speed and come back to normal. At times the engine would start to rev with the erratic speedometer, and applying the brakes lightly stopped the engine revving. It stopped after a few mile and didn’t happen again on that trip. I took it to the dealer the next week and they didn’t find any engine codes thrown, and the car seemed to check out fine.

After I got a slow tire leak fixed on the 1/24/13, the speedometer acted erratically after leaving the dealer, and I remembered they washed the car before I left. I then took it back to the dealer on 1/28/13 but they inspected the DTS again didn’t find any codes or problems. I had them wash it and I drove it with a service technician, since the problem seemed to occur in the wet, but it did not occur again that day.

To make the problem more interesting, I went on a road trip on 2/9/13, a dry, sunny day, and the problem started happening again. I was twenty miles from the house when the cruise disengaged and the speedometer was acting erratically. It didn’t happen again until I reached my destination about 90 miles away and was heading back home. This time I took a video with the Lumia cell phone. I also had OnStar run diagnostics while it was happening, but they didn’t see any problems. It stopped acting erratically about 60 miles from the house, but I drove the DTS directly to the dealer. They checked the car out again, no codes thrown and I wasn’t able to duplicate the problem when driving with a service technician.

Here is a link to the videos on SkyDrive - http://sdrv.ms/11T5R7F. Rpanzera – does you speedometer behave the same way?

There’s a speedometer needle drop just under a minute in the first video, and I get the Speed Limited to 108 MPH about 3:20 into the first video. I’m calling OnStar to run diagnostics after that in the videos, but they didn’t find anything unusual.

I took the DTS on other 200 mile long road trips after that incident and didn’t have any problems. It did happen occasionally in wet weather around town, but I was usually close to my destination and the problem didn’t re-occur once the car was restarted. I had the oil changed on 5/7/13 and I asked the dealer to check out the vehicle speed sensor and it looked fine. They washed the car before I left and the problem happened again on the way home. I took the DTS immediately back to the dealer, had them wash it again and then drove with the service technician, and of course, the problem did not occur again. They suggested I leave the DTS with them a few days so they could inspect it more in depth. This last week was the first time window I had to leave the DTS with the dealer. Any suggestions or ideas are welcome. If the dealer figures it out, I’ll share with the group.

Superjim
06-22-13, 04:57 PM
NCDTS...
I watched the first video... That is really strange.
What is that GREEN symbol/icon in the tach??
A couple of times it flashed ORANGE...
Mine doesn't have that green icon...

NCDTS
06-22-13, 07:19 PM
Hi Superjim - that is the lane departure warning symbol. It's green when active and functional - meaning it sees the lane I'm in - then flashes orange when I am leaving the lane without a turn signal on. I'm not good at both driving and filming at the same time <g>.

Eddie39
06-22-13, 08:07 PM
I've seen this on a couple of Chevy Tahoes and both had bad speedometer clusters.

danog
06-23-13, 03:22 PM
Rpanzera & Ncdts

Intermittent Conditions are the worst things to track down. Itís when you go to the dentist the tooth stops aching. Did they check the EBTCM for codes? It sounds like it might be in the GM high speed LAN. Have them put the J-42598-B vehicle data recorder with data capturing capabilities in your car. They can program it to your car to record the data automatically or manually. ALL GM dealers have them .GM sends them to all dealers. It looks like a large coffee cup. I have had customers driving around for a month until it happen. We download it to a computer and read the data to see what went wrong it a great tool for intermittent.

Tom..

NCDTS
06-23-13, 04:59 PM
Hi Tom, my dealer did check for codes, but I don't know if they checked for EBTCM codes (I assume EBTCM is Electronic Brake Traction Control Module). Appreciate the suggestion for the GM vehicle data recorder, I'll ask them tomorrow about the EBTCM codes and the data recorder if they haven't found any useful. I was thinking of getting a Bluetooth ODB scan tool and logging to my laptop if they didn't find anything, but I'd rather be running a GM recorder if needed.

rpanzera
06-24-13, 08:17 AM
Thanks for responding. I installed another vehicle speed sensor this weekend, but makes no difference. I am going to take it to Sewell Cadillac today and let them tell me what they think. It is pretty easy to get it to act up. LOL...I've had several times when it registered zero and would not shift out of first gear. I'll let you all know what I found out.

Thanks Again,

Ric Panzera

NCDTS
06-24-13, 07:27 PM
Heard back from the Service Advisor today. Their technicians reviewed the information with GM techs and they are replacing the speedometer cluster. Part should come in tomorrow and I hope to have the DTS back by Wednesday. It might be a couple of weeks before I have the opportunity to take it on a road trip and really test it out. Appreciate everyone's help and suggestions on the issue.

Cadillac Cust Svc
06-25-13, 08:25 AM
Thanks for responding. I installed another vehicle speed sensor this weekend, but makes no difference. I am going to take it to Sewell Cadillac today and let them tell me what they think. It is pretty easy to get it to act up. LOL...I've had several times when it registered zero and would not shift out of first gear. I'll let you all know what I found out.

Thanks Again,

Ric Panzera

Hello Ric,

I see your interactions with the other forum members and see their advice on your situation. Please keep us updated after your dealer visit, and if there is anything else you would like to discuss, please reach out to me via private message.

Laura M.
Cadillac Customer Service

rpanzera
06-25-13, 12:14 PM
I took to Sewell Cadillac in Dallas yesterday. They found excessive resistance/loose terminal tension at transmission control module connector. They removed and adjusted terminal tension to ensure a positive connection and road tested. I picked it up and drove for about 20 miles before the same issue resurfaced. Am taking back to Sewell in the morning. I have been a customer of theirs for at least 25 years and this is the first time they have ever failed to correct a problem, so you can figure it is probably a real "stumper".

Cadillac Cust Svc
06-25-13, 04:59 PM
I took to Sewell Cadillac in Dallas yesterday. They found excessive resistance/loose terminal tension at transmission control module connector. They removed and adjusted terminal tension to ensure a positive connection and road tested. I picked it up and drove for about 20 miles before the same issue resurfaced. Am taking back to Sewell in the morning. I have been a customer of theirs for at least 25 years and this is the first time they have ever failed to correct a problem, so you can figure it is probably a real "stumper".

Thanks for updating us on your situation Ric. I am sorry your vehicle experienced the issue again right after picking it up. I see you are taking it back to the dealership tomorrow. Continue to keep us informed please!

Laura M.
Cadillac Customer Service

rpanzera
06-27-13, 04:43 PM
I picked up the car a while ago and all seems well. Sewell technician reported that there was an "intermittent open/high resistance in circuit near the speed sensor connector. Tested and was able to make the speedometer inoperative by moving the wires near the connection. Replaced the speed sensor connector pigtail, soldered the connections and insulated with heat shrink, tape and electrical conduit. Then disconnected the transmission control module connector and checked a/c voltage on pins 16 and 41 from the speed sensor--measured a/c voltage of .2xx and higher which varied with the vehicle speed accordingly indicating proper operation. Road tested vehicle 18 miles and speedometer continued to operate properly as designed."

Because this was the second trip for this issue, Sewell asked me to pay for the parts ($58.22) and they did not charge me for the labor.

As I mentioned in my earlier post I have been a Sewell customer for more than 25 years. They are the best, most professional people with whom I have done business.

Tom's Caddy
06-28-13, 10:56 AM
Great news.:)