89 GM3800 VIN "C" Service Engine Soon light

[Guest crazytrain2]

I've recently had an intermittent<o:p></o:p> SERVICE ENGINE SOON yellow dash light on a 1989 GM3800 (3.8L) VIN "C" engine (same as REATTA). As it only comes on intermittently will the error code be stored if I use the "jumper on the ADL, count the flashes" technique to determine the cause?

Whatever the cause it hasn't had any real noticable effect YET, which by me even making such a comment pretty much guarantee's it will soon...lol

[Guest Mc_Reatta]

Yes it should. Could take it to you FLAPS. Believe their readers will report OBD1 codes too. Fast and free.

[D-a-n-i-e-l]

you can jump pins a and b with a paper clip. Then turn the key to run. The SES light will flash:1 time then twice, and repeat three times. The the following flashes will come in sets of three. so 34 will be three flashes followed by four flashes and repeet three time for each code. Once the ECM has rann through all stored codes it will flash 12 three more times.

Write down all codes disconnect the battery then drive until the light sets once more. This will ensure you are getting only current codes and not chasing historic or fixed codes.

[Guest crazytrain2]

Mc_Reatta - Thanks but I tried Advance, A/Z and O'Reilly none had scanners for pre '96' vehicles

Daniel - Thanks for the tip, was what I was gonna try , good thing you mentioned the "12" flashing three times as I had forgot.

As I finally got around to pulling the panel under the dash much to my agravation the only module there was for the brake system (an ATM Brake system module with cable connected to it) There were no Data Link Connectors. Good grief, anyone have any idea where else I should look for the ALDL? Keep in mind my vehicle is an 89 Electra Park Ave Ultra - same engine as Reatta & Teves brake system as well.

Here's what's happening: Service Engine light comes on at low RPM, misses 2 or three times when accelerating and feels sluggish, at about 15-20 mph light goes off, about 5 seconds after light goes out engine sluggishness goes away (slight surge) Even the manual says the ALDL is under this dash panel - go figure.

I'm guessing MAF, Oxygen Sensor, Coil or fuel system related (pump/filter/injectors) but can't see service engine light going off if fuel related.

Oh by the way it has new plugs, wires and alternator (about 1 yr old each and ran fine until about 4 weeks ago)

Thanks guys!

[padgett]

It is under the dash somewhere, have even seen on passenger side and inside a console. Might ask a Buick dealer.

I used to see OTC 2000s with a GM cartirige on ebay all of the time for @20-$40 but the supply seems to have dried up. Might look on your local CraigsList - 2000 was replaced by the 4000 which can do OBD 2.

Edited March 30, 2013 by padgett (see edit history)

[Guest crazytrain2]

Well I managed to find the ALDL (To avoid any confusion please note this is a 1989 Buick Electra Park Ave Ultra)

It is under the dash just left of the passengers seat below are the trouble codes and description followed by my plan of action. Welcome any tips, suggestions, warnings or even a vote of confidence.. lol

13 Oxygen sensor voltage stays between 0.35 and 0.55 volts for 30 seconds when the TPS signal was above 0.55 volts. The engine had been running for at least 40 seconds at normal engine temperature.

<o:p> </o:p>

21 TPS voltage was above 2.5 volts for 5 seconds when engine was running and air

flow was less than 15 gm/sec.

<o:p> </o:p>

*39 Torque Converter Clutch (TCC) circuit.

<o:p> </o:p>

41 Cam sensor signal was not received by PCM for the last 2 seconds while engine

was running.

Right now my plan is to replace the Oxygen sensor and the Throttle Position Sensor, then go to church and pray like H_ll !

Dummy that I am when I installed a new harmonic balancer I didn't install the cam sensor (WHICH I HAD) but it was 110 degrees in the shade that day @#$%^.

So much for the votes of confidence, how about a best of luck?

*Code 39 Description from a Haynes manual not specific (nor was it even listed) for a 1989 GM3800 VIN "C"

[Ronnie]

It appears from your interpretation of the codes that you might be looking at a list of OBDII codes or something.

I would recommend only changing one sensor at a time and test before changing another one.

This is a list of codes for OBDI.

ECM Diagnostic Codes - Reatta Owners Journal

[Guest Mc_Reatta]

Replacing O2 sensor is OK if its been awhile.

TPS may just need to be adjusted and not replaced.

Your confusing cam sensor with crank sensor. Crank sensor doesn't set a code, engine just won't run. You need to replace the cam trigger magnet.

Save TCC for last. May just be bad connection at socket or may be something else. But it can wait till you get the engine running right again.

[Machiner 55]

CT,

Where a bouts in Northern IN. are you.If you are close to Valp., I could come over and cheer you on.

John F.

[padgett]

41 is Cam Sensor Circuit but, if the magnet is lost, SES will never go out. IAC has no adjustment, just often needs to be cleaned of gunk. Need to clean inside TB where it mounts also.

TPS should read between .38 and .42v at idle, over 4.0v at WOT and be linear in middle with no drop outs.

Can download the 89 Reatta manual from reatta.net/docs.html - registration was a requirement from GM to post - the engine diagnostics and powertrain information are the same for all "C".

[Guest crazytrain2]

Thank you for all the feedback!

Ronnie - As you mention, I'm gonna do the O2 Sensor, check for effect then (if necc) the TPS

MC_Reatta - I love you man! LOL - thanks for keeping an eye on me (cam sensor vs. crank sensor)

Machiner - I appreciate the offer but between my wife and lazy Son (just kidding) I think I'm good. If it takes me until July though I might take you up on that at the show.

Padgette - What's a WOT (I couldn't resist that one..lol) I don't have a multimeter so I'm unable to test. If you have a link to a very basic and inexpensive one which would cover most general purpose automotive applications I sure would consider getting one.

Thanks again !!!

BTW - This is the site I used for the trouble codes (need to scroll down to 88-90 VIN C)

http://www.troublecodes.net/GM/

Edited April 1, 2013 by crazytrain2
Added link (see edit history)

[Guest Corvanti]

an inexpensive multimeter? Search results for: 'multimeter'

[padgett]

Harbor Freight (2 in Orlando) is my choice for inexpensive "junk yard" tools. Best deal rught nowfor a DVM is the backlit 7 function 92020.

ps Wide Open Throttle aka pedal to the metal.

[Guest crazytrain2]

I have an O2 sensor on order which is due in on Mon. In the meantime I'm trying to educate myself (no easy task) on the TPS and the Cam sensor / cam magnet. TPS seems pretty straight forward but have a few questions on the Cam sensor and magnet.

First where is the sensor? I read that it is located behind the water pump pulley but danged if I see it. I've attached a pic of a water pump on a 3.8L engine with pulley removed. Need some direction on where to look for the sensor. Then am I correct you can remove sensor and using a small mirror and light look through the sensor hole while someone else slowly turns over the engine (using the crankshaft bolt) and see if the magnet has fallen out of the camshaft gear?

I know there's an easier method with multimeter just haven't gotten there yet..lol.

THANKS!

[2seater]

I have an O2 sensor on order which is due in on Mon. In the meantime I'm trying to educate myself (no easy task) on the TPS and the Cam sensor / cam magnet. TPS seems pretty straight forward but have a few questions on the Cam sensor and magnet.

First where is the sensor? I read that it is located behind the water pump pulley but danged if I see it. I've attached a pic of a water pump on a 3.8L engine with pulley removed. Need some direction on where to look for the sensor. Then am I correct you can remove sensor and using a small mirror and light look through the sensor hole while someone else slowly turns over the engine (using the crankshaft bolt) and see if the magnet has fallen out of the camshaft gear?

I know there's an easier method with multimeter just haven't gotten there yet..lol.

THANKS!

[ATTACH=CONFIG]186380[/ATTACH]

It would be just out of frame on your photo, on the left side, below the water pump body. It's located on the front engine cover that the water pump is mounted on. It is black, and is a 90* design with the connection facing toward the rear. The sensor is attached with a single bolt and is O-ringed where it inserts in the hole.

[Ronnie]

There are photos here that will show you exactly what you are looking for:

Simple 3800 Cam Sensor Magnet Replacement - Reatta Owners Journal

Thanks to Padgett for this tutorial.

[Guest crazytrain2]

Holy headache Batman! There's 3 hours of time spent searching that I'll never get back.

That is precisely what I was looking for !!!

Thanks Ronnie and Padgette !!!!

[Guest crazytrain2]

Well I changed the oxygen sensor (used a Denso part), disconnected battery ground for 5 minutes or so before starting and it seems to have made matters worse. Engine now "chugs" when running, SES light doesn't come on until engine gets warmed up and although it does turn off, it seems to stay on for longer period of time. Have yet to run another diagnostic but looks like a new TPS is next, followed by a Camshaft sensor if AEF.

Feels like the entro to a B movie - "you'll laugh, you'll cry, you'll kiss $25 goodbye"

[Ronnie]

Since you disconnected the battery you should drive the car around for a while if you haven't done so. The ECM needs to go through "learn" mode before the engine will run correctly. That could account for the poor idling.

[Guest Mc_Reatta]

If you don't have a cam position signal, coordination of the fuel pulse with the spark is a crap shoot. Can run differently with each start. Do that next and you may not have to do anything but adjust the TPS idle position and allow you to go to more movies.

[Guest crazytrain2]

Sounds like a plan MC_Reatta, someone else said that if it's a cam sprocket magnet that has fallen off, then the SES light would continously lit. (ie. not on and then off) so hopefully it is only the camshaft sensor. It's only been since last Summer but I'll pull the IAC and clean it the seat again as well. I'm abit worried though, my gut is telling me it may be a MAF sensor issue hiding behind all this.

Ronnie - yeah I took it out on lightly traveled highway and maintained 35-40 mph for about 15 mi. to refresh set points. thx tho

mw

[Guest crazytrain2]

With the new O2 sensor installed, I cleared the diagnostic trouble codes, drove for a while at speed, and then ran another diagnostic (before I install the new cam sensor). I now only have 2 of the original 4 codes showing up - 39 and 41. Hopefully the cam sensor will at least take care of the code 41 issue.

One thing that puzzles me is that the SES light only starts to light up after the engine warms up and even then is intermittant.

Is this typical of a cam sensor (and not a missing interuptor magnet) failure? I can understand how if the magnet were missing SES light would be on constantly.

[Guest Mc_Reatta]

Not typical failure mode. Intermittent failure could be bad connection, dirt built up on the sensor or magnet, or a degraded interrupter that is just hanging on.

Need to take a look at the wires and connector, sensor and interrupter and see if something isn't right.

[Guest crazytrain2]

Well here goes the on-going saga of mark's most excellent adventure.

I installed the new Camshaft Position Sensor, which resulted in a continuous SES light (no longer on again off again) and code 41. That, an odd "wear pattern" on the old Cam Pos Sens (see pic) and subsequent visual inspection of Camshaft Position Sensor Interupter Magnet (what was left of it) told me it needed to be replaced.

Old Cam Pos. Sensor Note: The "wear pattern"

I used Pagett's "quick fix" method to replace magnet, (worked like a charm so far). I disconnected battery to clear codes, restarted and NO MORE SES LIGHT!

However something is still not right, engine still has chuggle issue. I'm hoping the plugs may have gotten fouled from running poorly for so long. Welcome any suggestions

Thanks all

Edited April 17, 2013 by crazytrain2
Forgot to include pic (see edit history)

[Guest Mc_Reatta]

Since you cleared all the learning registers when you pulled the plug on the ECM, you may just have to drive it awhile while it relearns you system.

But go back into diagnostics and see if any new codes come up.

If it doesn't improve, any codes or lack thereof give clues as to what else may be wrong.

[Guest crazytrain2]

Well I've givin Ole Betsy some run time after clearing codes and although I now only have one DTC--> 21 TPS High Voltage (SES light is NOT on) the engine is still running terrible. No power / acceleration , misses / coughs under load and after it's warmed up. I haven't checked TPS yet (I'll explain later) but I'm also wondering if the CAT might be clogged (but it's less than 3 yrs. old <20K Mi)

I've borrowed a friends SnapOn MODIS scanner and plan to scan sometime tomorrow. I am not at all familiar with using this type of diagnostic tool and somewhat skeptical of how much use it will be for a OBD1 vehicle. If anyone knows what data I should save and if I can post it here might help with diagnosis I would sure appreciate them sharing with me.

thx again

[padgett]

My experience is bad running above idle with no codes is either secondary ignition (coils, plugs, plug wires) or fuel pressure (pump, filter, regulator). CATs rarely fail/clog.

As to what to scan I am not certain what your car supports but the usual - temp, rpm, o2, o2 counts, blm, fi, advance, tps, knock - should be available. Just strobe through them.

[Guest Mc_Reatta]

If you haven't already, go here and register for access to the online FSMs:

Reatta Data Page

Once your granted access, select the 1990 FSM link. 89 has same info, but it's easier to find section in the 90 FSM.

Then scroll down to the chapter link for "08D2 Computer System Diagnosis" and start reading.

Here's some of the data the scan tool will reveal:

This is for closed loop, warm idle.

[TexasJohn55]

Hello Crazy, What Padgett said is right on. I have owned an '88 Olds 98 for many years, Darn good engines, one of GM's finest. They do seem to be sensitive to ignition issues, especially plug wires. Misfire under load is first sign. I also suspect that bad plug wires led to my multiple coil pack failures over the years. Bad plug wires kill coil packs from my experience. You can check wires with ohmmeter but you may as well replace them. Yes I already had to replace magnet on my cam gear, years ago, without the benefit of this forum, took awhile to figure that out. Oddly enough, it never affected performance or emissions, just dang light on. Back on subject, maybe it is time for a general tune up. Fuel pressure and regulator function can be easily checked also while you are under the hood anyway. You can also listen to each injector fire with a stick or screwdriver held to your ear while touching each injector. A distinct clicking should be heard from each one when idling. There is also a spec for resistance if a tune-up doesn't fix your issues. Good luck, TexasJohn55

[Guest crazytrain2]

Dang it I forgot to mention in last post that I just installed new Autolite plugs and wires, sorry about that. Just watched a short video on doing a TPS voltage "sweep" test with a scanner. Thanks very much for all the help.

[padgett]

I prefer Rapidfires.

[Guest crazytrain2]

This just keeps getting more interesting and confusing by the day. I ran an engine scan yesterday which showed No Current Trouble codes and 1 in history (the code 21, which I expected) However I goofed trying to save the data so I ran another scan today. This time SES light was on and current code was 44 (lean fuel mixture). I've included some of the data from this scan below. TPS signal seemed fine (.4 V at idle up to 4.74 at wot with no dropouts) So I am now leaning towards the fuel system (pump, regulator, filter, injectors) as the source of my pain. And as suggested by John (thank you for the tip) plan to run the screwdriver injector test(s) and rent a fuel pressure test kit from O'reillys to check fuel psi, also pull vacuum line from regulator to see if it's bad.

I took time to pull the 3 front plugs just to have a look see one of them showed sign of detonation issue (white powder) hope that's due to lean fuel mix. I'm wondering if I should also clean the EGR valve?

I'm considering investing in a 2nd vehicle - A Tow Truck...lol

Thanks MC, John, Padgett, Ronnie, and evryone for your help!!

[Machiner 55]

CT2,

Why rent when you can own?

Harber Frate has them on sale for $19.99. There's one in SoBend.

John F.

[padgett]

That looks like a vacuum leak to me.

[Guest Mc_Reatta]

There's something amiss with the MAT reading as reported. Not sure if it's in F or C, but either way that's a high reading. Doubt if it's a major issue though.

[Guest crazytrain2]

Still chasing this engine issue and although it's running better I certainly can't take any credit for it. I ran a couple more data scan's, one at idle and one at 2500 RPM's (see pic for data) I hoped to aquire fuel trim numbers because I read "For a suspected vacuum leak, note the fuel trims at idle and increase engine speed to 2500 RPM and hold. If the STFT immediately decreases and moves to acceptable levels and the LTFT slowly starts to come back down, you have a vacuum leak" So now I plan to try the "propane" vacuum leak test. (Probably starting to see why my sn is Crazytrain huh?...lol) Any other thoughts, comments, life insurance beneficiary requests?

Really appreciate the help, sorry this one is dragging out for so long.

mw

[Guest Mc_Reatta]

Despite having a coolant temp over 200F, your shown as still being in open loop with very low O2 voltage and no cross counts.

Try disconnecting the O2 sensor and see what the scanner shows for O2 voltage then. Should be around 450 mv.

Again your MAT sensor readings are way high. It shouldn't be that high in Death Vally on a record hot day.

[TexasJohn55]

Crazytrain2, Any luck yet? By the way, what type scanner did you use on your '89 "vinC" Engine? TexasJohn

[padgett]

Open loop is why the BL is 128 and the FI is 150. With those coolant temps it should go to closed loop in about 25 seconds after starting.

[Guest crazytrain2]

No luck as of yet, still has a bad miss. Unfortunately I really can't address the problem further for another week or so. I read some more of the reatta.net troubleshooting info and saw a couple things that I thought might apply to my scan info:

1) A poor ECM ground at the ignition module ground can cause FI and or BL to read 150. Note: My scans all read BL = 150

2) Closed loop (May go Open with extended idle) Note: The scans I did which showed open loop were taken after probably 15-20 minutes idle time.

So gonna check and clean ICM mount and run another scan.

John - I scanned using a Snapon MODIS with the GM-1 (connects to ALDL) and 12V (cigarette lighter) power supply adapter's. Can't get any fuel trim numbers like you can with the Reatta diagnostic screens.

Padgett - I also checked for any vacuum leaks (using propane and listening for higher rev's - no joy).

I also must admit to my lack of a multimeter yet as well - no excuses, just admittance and guilt.

Thanks again guys, I'll post as I get to the bottom of this. In the mean time and as always advice is most appreciated.