: tranny light comes on, i need opinions!

09-26-06, 12:45 PM
I've posted about this before, but really didn't get much input, so I'm gonna try it again. I have a 97 Cat, 110,000 miles. It runs really well, except after driving it about 25 miles or so, the tranny light comes on and it goes into "limp-home" mode. You can either downshift manually or just turn the car off and back on, and all is well again. This started about a month ago. I changed the tranny filter and fluid, and it changes perfectly, so I'm pretty sure it's not an actual transmission problem, but rather one of the many sensor type problems these cars have. Does this car have a transmission fluid temp sensor, and could this be causing it after it heats up? Or could it be the transmission control module? I could really use some input from you guys. I really love this car when it's right, but god it's a pain when it's not. If you've had any experience with this at all, please give me some ideas, I'm at a loss, and I don't want to just keep throwing new parts at it without having a clue if it'll work or not. Thanks in advance!

09-26-06, 01:08 PM
Less than a year ago I was interested in a used Catera being offered for sale by a large (and I mean LARGE) Chevy dealer. This dealer has a huge service department with every manner of tool and tech on the scene. It is a busy, humming service operation.

I learned the Cat had a nondescript (i.e., poorly defined) transmission problem the first time I went in to look at it. The car was not there on the lot. And it was not being worked on in this dealer's large service department. It had been sent to a local transmission shop to have the problem fixed!

The take-home lesson for me from all this:

If a large GM service operation, with all their techs and resources, would not tackle this Cat transmission . . . . what chance would I have?

I continued to follow up on this because I was interested in the car. But when it took two weeks for the transmission shop to complete their work I decided to look elsewhere.

09-26-06, 03:36 PM
Mine did it more in the morning, but similar symptom. If I shut it down and started back up, all was OK.
Mine turned out to be the nuetral safety switch. A little tricky (tight) to install, but not too bad. It was about $150 if I recall. Acces is from under the car on the side of the drivers side of the tranny.
Good luck

09-27-06, 07:22 PM
I've recently joined the forum to try and helpa coworker with his Catera (southern California). His car is experiencing similar problems (I think he said it was a 98 or 99) to what you describe.

He also indicated that the trnas would shift out of gear occasionally at random (but not often).

I'm not sure what it may be, but I'm going to try and drive it tomorrow. I'll try to post more detailed description of problem after that time. I believe it is related to valve body electric shift solenoid or maybe the neutral safety switch....

He also mentioned that he has a coolant leak and I want to look into that (he's not mechanically inclined - we keep him away from the hardware at work!)....

09-28-06, 02:46 PM
Any idea where to get this neutral saftey switch besides from the dealer? I can't find it at any regular parts stores or Rock Auto. Also, anybody else that has had this light come on, please let me know what was causing it for you. I need all the help I can get from you guys, and the more people that tell me what their problem was, the more comfortable I'll feel putting money into a part. I get so tired of just wasting money on stuff for this car..lol

09-28-06, 07:26 PM
I hate to have you replace it and not fix your problem, but it worked for me. I ended up paying a dealer $80 for a diagnosis and bought the part at Rockauto for $135. Dealer wanted around $400.
Here's the link. Go to the electrical switches and relays section.
https://www.rockauto.com/dbphp/mak,CADILLAC,2001,CATERA,1371136,3.0L+181cid+V6+FI +(R)

09-28-06, 07:27 PM
Sorry, the link got cutoff, but you'll see it in the electrical switches and relays section.

09-29-06, 09:43 AM
Hey passionaterage, I also have a 97 and it does the exact same thing as yours. Let me know if ya get it fixed and how ya fixed it. I have heard that it could be the neutral safety switch in other posts also, but hate to spend 150 bucks without being sure.

10-02-06, 06:20 PM
Come on guys, I'd like some more input! Surely more people than this have had the tranny light come on. I'd just like to know what you found out caused yours. Also, anyone else had the neutral safety switch cause this?

10-09-06, 09:14 PM
I had the exact same problem & it was the Neutral Position Sensor (Neutral Safety Switch / PRNDL Sensor depending on who you ask). I got it at Autozone for around $130-140. Should only take about 1 hour or less to replace if you've got tools & know how to use them. It is a pretty tight fit. It's located on a shaft coming out of the drivers side of the transmission. There are 2 10mm bolts holding it on & then the center bolt on the shaft. BE CAREFUL with the shaft bolt. I didn't put much torque on mine & it snapped the shaft clean off. I suggest starting to spray yours with WD-40 or similar now so that when you finally get the part, it won't do that. Anyhow, the first 10mm bolt is easy to get to, but the second is a royal pain. It's completely out of site & the only real way to know where it is is by either touch or by looking at the new one for reference. You'll also want to remove the heat shield before removing the 10mm bolts to make it easier. After the bolts are all off, then just pull/wiggle the switch off of the shaft. Then disconnect the two poorly located wire connectors & install the new one in reverse order. Hope that helps. Also, if anyone wants to know, the main reason that I'm seeing these things breaking is because the part thats connected to the shaft is plastic & snaps. Thus, the shaft turns, but the switch doesn't. Oh, I almost forgot. Leave the 2 10mm bolts loose when you put it on, then try to start the car. If it starts fine, then torque them down, if not, then rotate the switch till it does.

10-17-06, 05:25 PM
Well I ordered the neutral safety switch today. I read enough posts about it that I'm willing to chance it. I sure hope this is the problem, everyone cross your fingers...lol. It should be here by the end of the week, and I'll update here when I put it on as to whether it fixed my problem or not. There's so many things on this car that can cause so many different problems, it's always a crap shoot. But the more input you get from people who have experienced a certain problem, and how they finally fixed it, the better you feel about trying something. Thanks again for the input guys, anyone else who has had this problem please tell us how you fixed it. It's really a big help to us folks that rather (or have to, because of price) fix it themselves.

10-17-06, 09:19 PM
Believe me, it's not all that hard. It's pretty straight forward once you've got the part & see where it goes. Had it not been for the shaft breaking on me, it would have only taken me about an hour or less to do.

10-23-06, 07:36 PM
So did the neutral saftey switch do the trick? Waiting to find out before I order one, Im really cheap

10-23-06, 08:02 PM
From my experience, if you read the computer & get these codes:

P1700 - Manufacturer Specific
Notes: The p1700 is just a code that the TCM sends to the PCM telling it to turn the light on because the light isn’t controlled by the TCM (in other words, ignore this code & check for other problems which is probably the P0705 code)

P0705 - Transmission Range Sensor Circuit Malfunction (PRNDL Input or Neutral Position Sensor)

Then it is most likely the switch. I also noticed that putting the car into sport mode after starting the car (before moving) that it would work just fine. So, sport mode must be somesort of safe-mode. If these are symptoms you are experiencing, I'm feeling pretty confident that this is your problem.

10-24-06, 04:08 PM
I'll be putting the switch in this Friday, so I will certainly let you guys know if that was my problem. But now I have less hope, since when I put mine into sport mode, it made no difference. Heck, who knows, maybe I'll get lucky. We could all use some with this car, right?

10-28-06, 02:45 PM
Well here's the update. I put a new switch on, and after 38 miles it did the same thing. Tranny light came on, went into "limp home" mode. Once again, when I turned the car off and back on, everything was fine. So it wasn't the switch. Anyone else have any ideas? I hate to take it to the dealer, they always charge so much to tell you the most expensive news. Please help!

10-28-06, 02:50 PM
By the way, I'm getting a P1870 code, if anyone knows exactly what that means.

10-28-06, 03:07 PM
By the way, I'm getting a P1870 code, if anyone knows exactly what that means.

Uh . . . take your pick:


10-28-06, 03:32 PM
Ok, I just did some research on this code, and it turns out GM put out a TSB for exactly this problem. The control valve body wears out, causing too much fluid to leak past once the tranny reaches normal operating temp. I found out that a company called Sonnex makes kits to repair these valve bodies. My question now is this, does anyone know the number of the transmission in these cars, specifically a 97?

01-09-07, 10:29 PM
Not sure what you mean by number of the transmission, but here's what model is in the catera:


Marks DTM Calib
01-10-07, 08:29 AM
Its a standard GM 4L30E as used in many GM units.....its actualy mega rare in europe.

If its dropping out when shifting from 3 to 4 then it will be the valve body issue. The sure fire way to proove it is to hit the sport button or manualy select a gear when it happens, if this recovers it without the warning light coming on then its a sure fire valve block problem...

04-22-07, 02:51 PM
Ok, so here's the latest update. I know it's been a while, I actually hoped I had it fixed. I apparently checked the tranny fluid wrong when I did the filter and fluid change. It was about a quart low, so I added Lucas tranny additive to get it up to the correct level. Since that time, it was a few months ago, I've taken several trips of 40-60 miles, and the light has never come on. Fixed, right? Wrong...lol. Today I went for a little trip of about 12 miles, and on the way home it came on again and went into limp home mode. Luckily, I've learned to keep a code scanner in the car so I can reset the light while driving. This does the same thing as stopping, turning the car off, and restarting it. It resets the code. The thing that's different about today that may not have been an issue the past few months is this....the temp. here in NC is in the 80's today. So outside temp. appears to be a major issue, as it was hot last year when it all started. My question now is this...does the Catera have a transmission oil cooler, and if so how can I check to be sure it's working properly? I sure would like to fix this thing. Any help would be greatly appreciated!

frank moran
04-22-07, 06:23 PM
p1870 is a trans slip code, there is a kit to repair the TTC apply valve in the valve body of the transmission. Check that out, assuming all the wiring is sound. This is a pretty common problem and fix.....

04-22-07, 09:01 PM
Actually, when this problem first started, I got the valve body repair kit. It's actually just a very small spring, supposedly stronger than the one it replaces. But to be honest, i realized that I have no idea where this spring goes...lol. Is removing the valve body something that can be done by the average shade tree mechanic? Are you able to remove it after you remove the pan? I wish I could find a picture of exactly what I should replace and where it is. Maybe a tranny shop would do it and not charge too much. I'm just always afraid that anytime you take something to them, they'll tell you you need a new tranny...lol.

frank moran
04-22-07, 09:16 PM
Actually, when this problem first started, I got the valve body repair kit. It's actually just a very small spring, supposedly stronger than the one it replaces. But to be honest, i realized that I have no idea where this spring goes...lol. Is removing the valve body something that can be done by the average shade tree mechanic? Are you able to remove it after you remove the pan? I wish I could find a picture of exactly what I should replace and where it is. Maybe a tranny shop would do it and not charge too much. I'm just always afraid that anytime you take something to them, they'll tell you you need a new tranny...lol.

I believe the kit also includes a reamer and an over size valve??? yes the valve body can be dropped however there are a number of ball check valves that you can drop and WO a manual you may cause yourself a lot of trouble. Talk to a good transmission shop (one that does only trans repairs or dealer) before you start throwing parts at it, this is a common fault code. Do a google and you'll see how common it is. You can buy for about $15 a manual for that trans. Again if you have not done this and your not set up with tools etc. and you start geting dirt in the valve body.... or you tear the 2 valve body gaskets then you have a mess on your hands. JMHO.

04-23-07, 03:34 PM
Ok, I got the kit out to look at it.It's a TransLab 4L30E valve body kit. It comes with 2 springs, a new shim, a small drill bit, and a tiny valve. But here's the kicker. It says tranny must be pulled to install this kit, it can only be used when rebuilding. So that settles that, it's not something I can do. Maybe I'll try to go talk to a tranny shop when I have a chance. I can't even tell that it's slipping, it's not noticable at all, but I guess it's doing something to cause the code. Luckily, this is not my only car, so it's not a live or die thing that I have it fixed right away. I just hate taking this car to any shop like that, it's always mucho money! Thanks for all the replies, I guess I've gone as far as I can go on my own. I actually got so mad with this car last summer I tried to sell it on ebay for $2500, no takers. They must have read up on how troublesome this car is. I sure wish I had!! Live and learn, I'm definately not made for a Cadillac...lol