Gentlemen,

I don't post much because I don't know very much, but I would appreciate some advice.

I have a 1999 Seville SLS Northstar with 130,000 miles that runs just fine. About a year ago the SERVICE ENGINE SOON light went on and I pulled codes P0716 and P0717.

Upon searching through this forum I found out that those codes indicate a problem in the transmission with the Input Speed Sensor. I also found out through this forum that it is very expensive to replace. I made the decision a year ago the the car was not worth the repair cost and I would drive it until the tranny quit and junk the car. Well that was 12,000 miles ago and the tranny still shifts smoothly and the car still goes down the road like a "stripped ape". I think the transmission is OK and the sensor is bad.

Now, here's my problem. I have to get the car smogged in California this year and knew I was going to have a problem with the SES light on. The devious person that I am thought I could erase the codes with my OBD II scanner and the smog tech would not be the wiser.
I found that I could get one or two starts of the car before the SES light would reappear.

At the smog test the car passed the visual inspection and even passed the emissions portion of the test, but the DMV computer picked up the fact that the self diagnostic system had not rebooted and failed the car. The smog shop has offered one free retest after the diagnostic system resets, but the SES light will be on.

Can anyone suggest a course of action to keep this car on the road?

Do I fess up to the smog tech and see if the ISS code is acceptable and is not related to the emissions and see if he will certify the test or what?

I apologize for the long post and I thank you for your assistance

Farmbroker.

 

I dont think that the P0716/017 wold cause a SMOG failure .. I am not sure.
what other codes have popped up?
Fix the cause and see if the the service engine light stays away ..


codes P0716 and P0717

GM issued a TSB # 00-06-04-037 to cover several GM vehicles, Cadillac not included in the list but yet, I be checking it per instructions. As usual, this falls under the 95% of all problems is either the connector or wiring and not the component.



The condition could be caused by an intermittent connection in the Input Speed Sensor circuit, most often found at the 20-pin connector to the wiring harness interface.



The input speed sensor produces a signal to the powertrain control module (PCM). If the PCM detects a large change of the input speed signal in an extremely short period of time (less than 0.8 second), it will set a P0716 code and the PCM will direct maximum line pressure. This could result in firm shifts and certainly codes.


If the vehicle is moving at speeds greater than 5MPH and the input speed signal is low or at zero, the PCM will set P0717 and command maximum line pressure.
Do not assume the input speed sensor is faulty; inspect the wiring harness between the transmission and the PCM, particular the 20-pin connector to make sure it is not being pulled on.


make sure that other components are not pressing on the connector body or forcing it open. Check for proper clearance between the connector and other components. Make sure the terminals are fully seated in the connector. Check for bent male terminals or loose female terminals. Also check the crimp on the terminals.

Lastly, read our instructions for the use of di-electric grease which should be considered.

 

Thanks for the response Stomper.

I don't have any other codes other than P0716 and P0717.

Is the 20 pin connector between the PCM and the transmission located next to the coolant reservoir and mounted on that portion of the fender well that covers the shock strut?

If so, that connector looks as if it has been subjected to steam and coolant overflow from the coolant resevoir. If that is not the 20 pin connector, could you describe where it may be located?

Thanks,

farmbroker

 

No. The Automatic Transmission Inline Harness 20-way Connector is located underneath the car on the driver's side above the engine frame right in front of the transaxle. Squeeze it hard with one hand and hold the other end while pulling gently and it will come apart.

Test terminals S and V on the transmission side for 1300 to 1950 ohms resistance. With the transmission side of the connector facing you and the alignment slot on the right 'S' is the left conductor on the second row from the top and 'V' is the second conductor from the left on the top row. If it is out of that range there is either a problem with the wiring or the Automatic Transmission Input Speed Sensor (AT ISS). There is a good description to dianose whether the problem is with the sensor, wiring or PCM in the service manual. If you are lucky the problem is with the wiring or connector, if not you have to pull the transaxle to replace the sensor.