Intermittent SES Light - 94 LeSabre

ssjones · #1 03-23-2006, 10:33 PM

My daughters '94 LeSabre has an intermittent SES light. She claims it surges and idles high when the light is on. Yesterday, I test drove it, no light and no problems. I did find the postive battery cable a smide loose, tightened that. Cleaned the throttle body, but it really looked pretty good. Decided to pop in a new air filter that was on my workbench. I found a sensor unplugged, leading into the air filter housing and thought for sure the source of the SES light.
Today she said the light came back on. I did a search on reading OBDI codes and didn't get a definitive answer. I did find this thread:

http://www.automotiveforums.com/vbul...k+Engine+Light
This sounds like I can check the pins and potentially use the paper-clip trick. Can anyone confirm or deny that possiblity?

The car has the 3.8L motor, new plugs, filter, fuel filter, 111k. I'm out of town this evening, but will be back home tomorrow. I appreciate any advice.

ssjones · #2 03-24-2006, 01:00 PM

I should also mention I put in an 02 sensor about 8,000 miles back. I called Autozone, they can't read OBDI but Advance Auto said they might be able to read the code, I guess the '94 is in OBD limbo. I'm thinking maybe the EGR valve, hopefully Advance can pull the code, I'm heading there now.

HotZ28 · #3 03-24-2006, 01:26 PM

A few of the first produced 94’s still had a “flash code” sequence programmed in the PCM, however after that, that program was eliminated; so therefore, you would need the scanner to retrieve codes and no more "paper clip" tricks!

ssjones · #4 03-24-2006, 07:57 PM

OK, Advance Auto pulled my codes. Interestingly, my OBDI connector is an OBDII style. The sales guy pulled these with an Actron reader:
PO112 - Manifold Air Temp Sensor Signal Low
(this is the sensor I had found unplugged and plugged back in)
PO122 - TPS Signal Low
PO561 - Cruise control vent solenid vent malfunction.

Bought the MAT and TPS. Found a vacuum line not attached to anything on top of the motor, ties in with the EVAP. I'll snap a digital photo later, but sounds like related to the Cruise control code. I cannot find an empty vacuum line fitting

The MAT sensor was a snap. The TPS sensor, on the bottom of the TB is held in by two screws (huh?) and I cannot access without removing the throttle body. However I'm cursing the GM engineers for the TB design. I have two of three bolts off. The third, under the throttle body is held in place by a two-bolt bracket. One bolt has easy access and was removed. The second is right in front of the exhaust manifold and I cannot get a 1/4" or 3/8" socket on it. Tried a wrench, the bracket has a lip preventing any attachment. Additionally, the bolt looks very rusty and the other side took a mighty effort to remove. Can anyone offer a tip on how to remove this cursed item?

ssjones · #5 03-24-2006, 08:06 PM

I should also say the wire connection lock for the TPS broke, just hoping that won't be a problem later (somehow). Guess I'll be heading to the GM dealer on Monday.

Here's a shot of the mystery vacuum line:
http://community.webshots.com/photo/...62237293CCgztI
The line on the right is the mystery line with the GM number markings. The line in the bottom, center of the hub runs to the EVAP canister.

ssjones · #6 03-25-2006, 10:56 AM

Not much luck here. Gave up on getting the throttle body off. Even got a 1/4" 13mm socket and hack-sawed it in half, still didn't give a good bite on the bolt.
My nephew is the service manager of a PA Buick dealership. I'll call him on Monday and talk to a Buick tech for advice. I gambled that the MAT also triggered the TPS code and put it all back together with the new MAT and old TPS. Car runs fine but after driving at speed, idles way too high. That TPS has to come off. I might be able to get it off with a pair of vise grips, if I can reach the screw heads. I could replace the straight head screws with a socket head or other fastener and be able to use one of those tools. That failing, the exhaust manifold has to come off the left side. Given all the time I've put in, that might have been the easieset route
Horrible design here on these components, very frustrating. Still have not found where that vacuum line runs, my Haynes manual only shows a "typical" EVAP system vacuum line routing. Can't imagine a line that long vents to fresh air, it has to go somewhere.
If anyone is reading this stuff, any advice appreciated.

HotZ28 · #7 03-25-2006, 11:11 AM

I have changed quite a few TPS's on Buick 3.8 engines using an offset screwdriver. No need to remove the TB.

ssjones · #8 03-25-2006, 11:52 AM

I just couldn't break either screw loose. I'll hit it with some PB Blaster and give it another try. Thanks for confirming it can be done - I'm going for the victory! I'll post my results, wish me luck & thanks.

HotZ28 · #9 03-25-2006, 10:08 PM

I love it when a person has persistence, determination and intestinal fortitude!!

mcqueary · #10 03-26-2006, 12:20 AM

An offset ratcheting screwdriver from Sears allowed me to remove and replace the TPS on my 93. I agree the design could have been more user friendly.

ssjones · #11 03-26-2006, 03:37 PM

I have the straight, not offsetting screwdriver, it won't fit. I'm going to try a manual, home lockset offsetting screwdriver, hopefully that works.
[image]http://s7.sears.com/is/image/Sears/00941715000?layer=comp&wid=190&hei=190&fmt=jpeg&ql t=75,0&op[/image]

ssjones · #12 03-26-2006, 06:11 PM

Quote:

Originally Posted by HotZ28

I love it when a person has persistence, determination and intestinal fortitude!!

If only there was a happy ending. I removed the thermostat neck, which gave me a valuable inch or two to manuever the offset screwdriver. The right screw came out right away. The left was all corroded and could not be budged. (I only tried the left before trying to remove the TB) It sat all night with PB blaster, but to no avail. I tried to grab the head with a pair of vise grips, which only twisted off the screw head (pan, head=crazy for that location). I then went to Lowes, bought two M4x.70-25mm hex-head bolts to replace the pan head screws. Also bought some matching nuts and attempted to back out the screw, but it just twisted off, breaking off flush with the TB housing. At this point I said screw it and decided to take it up to our local service station (friend owns) to see what he can do. NOW the TB has to come off to use an extractor or easy-out on the broken screw. Fortunately, the car started and ran fine without the TPS, but of course set the SES light.
I'll report back on what the garage does to remedy the situation.

ssjones · #13 03-28-2006, 09:10 PM

Shop charged me $116 to remove the TB and put on the sensor I bought. I talked to the tech and he used a stubby 13mm wrench, said it just barely worked. I picked up a stubby set of wrenches at Sears twice last year, and decided I wouldn't need them. He also used the 4M-70x25 mm hex bolts to install the new sensor, so subsequent changes should be a lot easier.

I still have to identify where that vacuum line runs. On the firewall, to the left of the brake booster, there is a small oval item. It has a hole in the center, I'm wondering if that hole is supposed to have a fitting for the vacuum line? I'm out of town again and will post a picture in the hopes that someone with a '94 can help me out.

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