95 Bonneville 3.8l vin.K wont start


Tonedog
10-02-2009, 12:25 AM
It gives me a code "122 Throttle Position Low", I replace TPS, but after clearing codes, the same code comes back & car still wont start...any suggestions?

HotZ28
10-02-2009, 07:29 AM
Check the voltage on the TPS with ignition switch ON, engine off. You should have 5.0v on the Grey wire with variable voltage on the blue depending on throttle opening. (Black is ground) With throttle closed, you should have .45v and progressively higher as the throttle opens to WOT, where you should see 4.0v - 5.0v. Your problem sounds like the PCM, but you need to investigate the obvious first.

Tonedog
10-04-2009, 10:24 PM
Thanks HotZ28, I did have 5volt power on the grey wire, the black wire was a solid ground, & the blue wire was nothing at all, this wire was traced back to the pcm, no shorts or open breaks were found, probing the harness coming from the back of the pcm, still nothing. This blue wire should be the refrence wire if im not mistaken. Im leaning towards what you said about a bad pcm now, since the blue wire has no signal coming from pcm, this means bad pcm, right? Also, i failed to mention that the car is running finally, but with a very high idle due to my tps situation, or now pcm situation

HotZ28
10-05-2009, 07:31 AM
This is not uncommon for the 94-95 PCM! You can get a rebuilt PCM for less than 100-bucks @ O'Reilly with a lifetime warranty - not a bad deal. BTW, good troubleshooting!

Tonedog
10-05-2009, 04:18 PM
Thanks again HotZ28, I suspected the PCM, but its always nice to have someone else comfirm it also, you are pretty knowledgeable with these cars. I've drove Mustangs my whole life, & I must admit, I miss it. This Pontiac has gave me problems since day 1. It runs fine one day, then bad the next, I replace sensor after sensor, thinking I fixed the problem, then the intake gaskets blow, along with the melted upper plenum hole for the egr stove pipe, which I had to repair just recently due to coolant lose & then ofcouse the hydro-lock when the cylinders filled up with coolant. Luckly this all happened in my own driveway at idle, so no further damage was done. Anyways, thanks again for taking the time to answer my questions & confirming my diagnosis, your definatly a life saver. As for the Orielly auto store, I've seen commecials on tv for them, but we dont have one around here yet, we need one tho.

Tonedog
10-05-2009, 08:09 PM
I'd like to pick your brain 1 more time HotZ28, if I may, once I get this PCM for my car & know it works, I'm gonna have to change out the drivers side window motor, & both back window motors also. Do you know how these door panels come off? There must be some hiden screws that I'm un-aware of cause the last time I tried to pull it off, I didn't have any luck.

HotZ28
10-05-2009, 08:25 PM
FYI, here are the PCM ID & Memcal specs. You may be able to find a used one @ a JY. All the cars listed below use the same PCM and you can use your existing prom. BTW, Click Here (http://cgi.ebay.com/ebaymotors/16183247-Pontiac-Buick-Oldsmobile-Computer-ECM-ECU-1995_W0QQitemZ150373614557QQcmdZViewItemQQimsxZ200 90917?IMSfp=TL090917239015r18812) for one on eBay. Good luck!

# 16183247 Elec Cont Module (ECM); (6-231, 3.8L)
Application: 1994-95 3.8 V6 SFI “L” L27
1995 3.8 V6 SFI “K” L36
1994-95 3.8 V6 SFI supercharged “1” L67
1994-95 truck 3.8 V6 SFI “L” L27

MEMCAL IDs: “L”: BMYU, …

Application:

BUICK LESABRE CUSTOM (1994 - 1995)
BUICK LESABRE LIMITED (1994 - 1995)
BUICK PARK AVENUE (1994 - 1995)
BUICK PARK AVENUE ULTRA (1994 -1995)
BUICK RIVIERA 1995
CHEVROLET LUMINA APV (1994 - 1995)
OLDSMOBILE 88 ROYALE (1994 - 1995)
OLDSMOBILE 88 ROYALE LS (1994 - 1995)
OLDSMOBILE 88 ROYALE LSS1995
OLDSMOBILE 98 REGENCY 1994
OLDSMOBILE 98 REGENCY ELITE (1994 -1995)
OLDSMOBILE SILHOUETTE (1994 - 1995)
PONTIAC BONNEVILLE SE (1994 - 1995)
PONTIAC BONNEVILLE SSE (1994 - 1995)
PONTIACTRANS SPORT (1994 - 1995)

HotZ28
10-05-2009, 08:38 PM
I'd like to pick your brain 1 more time HotZ28, if I may, once I get this PCM for my car & know it works, I'm gonna have to change out the drivers side window motor, & both back window motors also. Do you know how these door panels come off? There must be some hiden screws that I'm un-aware of cause the last time I tried to pull it off, I didn't have any luck.Some good info from our archives, learn to do a search, you'll be surprised at what you can find: Click Here (http://www.automotiveforums.com/vbulletin/showthread.php?t=376761)

Tonedog
10-06-2009, 03:06 PM
Thanks again, I found this site from a google search, I didnt realize this site had so much info.

Tonedog
10-07-2009, 03:48 PM
Well, I finally bought a new PCM from AC Delco, cleared all codes, but my same codes comes back & still have a very high idle, I'm guessing I need to replace the Prom chip next, I just wish there was a way to check these things first without going broke buying everything, these cars are ridiculous....I miss my Mustangs!!!

HotZ28
10-07-2009, 10:58 PM
Are you absolutely sure the tab on the TPS is in the correct position?

Tonedog
10-08-2009, 02:15 AM
I thought these tps were not adustable, I removed 2 small screws & unplugged it & came right out, put new 1 in the same way. But, now that you mention that, I will give it another check. But, even if the tps is in wrong position, would that trigger the code 122?

HotZ28
10-08-2009, 10:24 AM
Thanks HotZ28, I did have 5volt power on the grey wire, the black wire was a solid ground, & the blue wire was nothing at all, this wire was traced back to the pcm, no shorts or open breaks were found, probing the harness coming from the back of the pcm, still nothing. This blue wire should be the refrence wire if im not mistaken. Im leaning towards what you said about a bad pcm now, since the blue wire has no signal coming from pcm, this means bad pcm, right? Also, i failed to mention that the car is running finally, but with a very high idle due to my tps situation, or now pcm situationI am sorry, I totally missed your comment shown above (in bold-underline) when I first read your post. (BONG) Now, after reading your post again, we need to go back to the TPS voltage readings. This is how it works; the Grey wire is 5.0v reference voltage from the PCM! The blue wire (TPS - output) should be variable with the throttle opening. The voltage reading from the blue wire is telling the PCM what the throttle position is. If you are not getting anything on the blue wire, the TPS is not varying the voltage and the PCM is not getting the info! :headshake You must find out what is happening here, be sure you are probing the terminal, or wire. You can use a straight pin to back-probe the terminal and clip the DVM positive lead to the pin. Be sure the ground lead of the DVM is attached to a good engine ground. Let us know what you find. :rolleyes:

Tonedog
10-08-2009, 02:23 PM
I rechecked everything like you mentioned, my DVM is built into my power probe 3, so I'm able to check power & ground while reading voltage. The grey wire (refrence wire) has 5 volts, the black wire (ground) is a solid ground, & the blue wire (variable voltage from tps) is 0.00, dead, even from the back of pcm. It's a brand new pcm & brand new tps, all wiring is in good condition, but I'm still at a lose.

HotZ28
10-08-2009, 04:17 PM
I think you misunderstood my last post, so I will try again. The PCM does not feed voltage on the blue wire to the TPS, it receives voltage from the TPS on the blue wire. To put it another way, you apparently have power (5.0v) going into the TPS, but none coming out!

Tonedog
10-08-2009, 05:58 PM
Yes, I understood your previous post about the (blue wire), Yes, I do have power going into the tps, & also is grounded. & your also correct that my (blue wire) is not sending anything out to PCM. I used my OHMS meter on the blue wire from the TPS plug to the PMC wire harness (unplugged) & my reading was 0.00, which tells me that there is no resistance, no breaks in the blue wire. So, why wont it send? Am I missing something? I also checked all the throttle linkage for anything out of the ordinary, made sure the TPS blade was correctly placed, & re-checked everything.

HotZ28
10-08-2009, 09:51 PM
Yes, I understood your previous post about the (blue wire), Yes, I do have power going into the tps, & also is grounded. & your also correct that my (blue wire) is not sending anything out to PCM. I used my OHMS meter on the blue wire from the TPS plug to the PMC wire harness (unplugged) & my reading was 0.00, which tells me that there is no resistance, no breaks in the blue wire. So, why wont it send? Am I missing something? I also checked all the throttle linkage for anything out of the ordinary, made sure the TPS blade was correctly placed, & re-checked everything.If your diagnosis is correct & your meter is reading the way it should, your TPS is DOA! I have never seen a new TPS not deliver some kind of output if it has 5.0v reference voltage! What brand is it? :frown:

Tonedog
10-08-2009, 09:57 PM
The TPS was replaced 3 times with the same results, the name on the box "Duralst", do you suspect a bad batch from this company, should I get my money back & go to a AC Delco dealer? Can it be that simple?

HotZ28
10-08-2009, 10:15 PM
It could be that simple! This is really hard to believe, even with Duralast (Rice) brand! It may be a Chinese conspiracy!

The_Mechanic_33
10-09-2009, 01:11 AM
just a thought and I feel dumb for asking,but are you moving the throttle while you are testing for voltage?

HotZ28
10-09-2009, 07:30 AM
Another early morning thought :) have you checked the TPS terminal pins, or have you checked the TPS resistance readings without the terminal connected? It is strange that you would have power going into the TPS, but none coming out, it's got to be something obvious! :screwy:

Tonedog
10-09-2009, 11:27 AM
No, I did not test the resistance on the switch itself, Yes, I did test the voltage while moving the throttle. I returned the (duralst) switch today & ordered one from AC Delco, should be here this afternoon, hopefully it works. The Duralst part said made in Mexico, so the chineese thery may be out...:p I'll post a reply later today after I get the new TPS.

Tonedog
10-09-2009, 04:28 PM
Well, I picked up the new AC Delco TPS, & installed it. Before doing anything, I verified that I have a 5 volt refrence with key on, engine off, (I do), I verified that I have a good solid ground, (I do), I verified that the blue wire OHMS out to 0.00, (It does), the blue wire should also have 0.44 volt minimum & increase to 4-5 volts at WOT, (It still dead) 0.00 volts. I verified that the TPS is actually showing resistance unplugged & increases resistance when I move the tps blade to WOT position, (It does). My question is, If I have a positive 5 volt refrence, & a solid ground going into the tps, why wont it send power out?

HotZ28
10-09-2009, 11:20 PM
If I have a positive 5 volt refrence, & a solid ground going into the tps, why wont it send power out?That's the million dollar question! :evillol: I assume your meter is capable of reading less than 1.0v.

Tonedog
10-09-2009, 11:54 PM
yes, it reads less than 1 volt, it will read in fractions of a volt

HotZ28
10-10-2009, 12:14 AM
You have 5.0v in, and the resistance changes with throttle opening, but no voltage out, you must have a bad terminal on the TPS, or Gremlins in the TPS eating voltage. :uhoh:

Tonedog
10-10-2009, 03:36 PM
Ok, we can finally end this thread, the problem I was having was caused due to my personal stupidity which I noticed today after I made up some homemade backprobes & re-tested everything with my DVM again. What I was unable to read was a negitive voltage on this signal wire, the reason it was a negative voltage & not a positive voltage was I kept installing the TPS swithes from left to right which placed the TPS blade incorrectly & therefor giving me a negative reading on the signal wire (Blue Wire). I removed the TPS while leaving it plugged in & attached to my DVM & moved the blade by hand & watched it go to 5 volts, so then I installed the switch from right to left which puts the blade in the correct position & gives me a positive voltage reading to the signal wire (blue wire). I cleared the code & it stayed clear this time. Car is running good again. HottZ28, I would like to thank you for all your time & effort you put in trying to help me solve my problem. I'm normally not this stupid, but this car had my brain fried for awhile & I wasnt thinking straight. Talking with you helped me to get back on track, so even tho you didnt fix anything sort-of-speak, you helped in ways I just cant explain....Thanks again!!!

Tonedog
10-10-2009, 05:01 PM
Are you absolutely sure the tab on the TPS is in the correct position?


I remembered you telling me this, but my brain was fried by this time & I didnt think all the way thru, so...you were absolutly correct, it was not in the correct position after all.

HotZ28
10-10-2009, 11:58 PM
Thanks for the candid feedback and don't feel bad, after 50 yrs of automotive experience, I still often fail to look for the obvious. I knew from your first few post, that you had some good knowledge and we could eventually find the solution. It pays to spend some time and try and adsorb what another person is trying to say on these forums. If we could have been in the same shop, this problem would have been resolved in a few minutes. Hopefully, this thread will help others!

Tonedog
10-11-2009, 03:54 AM
I AGREE!!! to all that, the working in a shop & diagnosing issuses, we would make a good team, it's pretty much all common sence, but having those sences at the right time when you need them, is what troubles us, thats why these threads are GREAT, were able to bump heads till we find a solution. I can normally figure things out pretty quick, thats why I felt so stupid, I over-thought & forgot the obvious... "I know better than that". Anyways, If anyone else has issuse, I'll be glad to join the thread & help you get your cars back on the road where they should be. Another thing I did to my car this weekend that made a big difference on all the electronics, I upgraded all my power & ground cables ( the cheap factory stuff ) & went to a marine store & bought the 1OT cable after measuruing what I needed & had them crimp all the 5/16th's terminals & heat shrink to all my cables. The bigger wire carrys more current, therefor giving all your electonics the power & ground they've been starving for, it made a big difference. Might wanna think about it for your own cars.:2cents:

HotZ28
10-11-2009, 10:36 AM
I upgraded all my power & ground cables ( the cheap factory stuff ) & went to a marine store & bought the 1OT cable after measuruing what I needed & had them crimp all the 5/16th's terminals & heat shrink to all my cables. The bigger wire carrys more current, therefor giving all your electonics the power & ground they've been starving for, it made a big difference. Might wanna think about it for your own cars.:2cents:Thanks for bringing this up, this is very good info for others to have! I have been doing the same upgrade since back in the mid-80's. In addition to soldered positive terminals, I use gold plated battery studs to attach the cables to the battery. I have never had an electrical problem of any type since this upgrade! Click Here (http://www.automotiveforums.com/vbulletin/showthread.php?t=761553)

http://img119.imageshack.us/img119/5162/batteryh.jpg

Tonedog
10-11-2009, 01:44 PM
Hey HottZ28, you got the same set up as me, gold terminals & all, except you used all black cables. Did you use HTML codes to post your pics on here? or is there a photo upload button I dont see.

HotZ28
10-11-2009, 01:52 PM
If you look at the top of the message box, you will see this icon http://www.automotiveforums.com/vbulletin/images/editor/insertimage.gif Click on it & enter the URL of your img from the img hosting service of your choice.

Tonedog
10-11-2009, 02:51 PM
thanks, I see it now, I'm still trying to get used to this site. So....Hott, do you moderate this entire site? I see other questions on this site I might be able to help out with, but I see you already replied to a few, I don't wanna step on any toes. How does that all work here? If you answer first, does the other person step back or does it not matter. I know to many replies can be confuzing to some people.

HotZ28
10-11-2009, 04:31 PM
Feel free to step in anywhere you want, you will not offend anyone. We are here to offer advice and help others save money. Different, or varying opinions are important & sometimes help resolve the problem sooner. This is how we provide a community service to those with less experience. Yes, I am a global moderator, which means I can moderate anywhere, but basically hang around the Buick Forms, where I share most of my "free advice"!

Tonedog
10-11-2009, 11:50 PM
Awsome, Thanks again HottZ28, it was a pleasure meeting you btw. I'm glad this site exist, like you said, where all here to save a buck & keep our cars running.

mrricha
01-02-2012, 12:47 PM
My 94 Pontiac Bonneville won't run either. I drove it to work it ran fine six hrs later tried to crank it and it turned over fine but would not start. poured gas down breather tube and engine fired right up and got me almost home. Poured gas agian to get rest of way home. tried starter fluid wouldn't work tried gas fires right up and runs till gas is used then will turn over all day but won't fire up. So what is a pcm anyway? Any advice am lost?

Tonedog
01-02-2012, 01:00 PM
PCM is the brain/computer of the car, also known as ECM...PCM=Power Control Module, ECM=Electronic Control Module. It accepts & delivers information to all the sensors. You mentioned having to pour gas to get car to run, have you checked for fuel pressure?

Drivingzzz
01-04-2012, 03:03 AM
RE: mrricha I have a 95 bonne sse with the same problem after many forums the common 'bugs' have surfaced thanks to the age of this car. Roughly 80% relates to a grounding problem on a ground plate located on the drivers side rocker panel. To check you will have to remove the door trim lifting up the carpet to expose. There are 7 black wires all connected to the plate. One of the wires yes goes to the fuel pump. What happens is you get a leak somewhere (mine in the lr wheel well) water gets in soaks the insulation under the carpet never leaves because the carpet is rubberized underneath and corrodes the plate. All the stranded wires turn black with carbon and quit or intermittently work. Some were 'black' 1 1/2 feet mine was 5! Trace the wire(s) from the plate until they are clean splice solder heat shrink etc. This corrected most although remember when troubleshooting there is always the possability of multiple issues. When you see the plate it will be obvious and you will have to take the plate apart. I would replace with a terminal strip and move to to higher ground.

mrricha
01-04-2012, 12:05 PM
Hey, thanks for answering Tonedog. No I have not tried checking for fuel pressure. I don't have the equipment and wouldn't know how. I 'm a shadetree and I totally wing it. If the problem is too tough I take my vehicle to the garage but times are tough so I have to fix it myself. It was running fine then It wouldn't fire up. I figure some kind of electronic gizmo went bad that I could just change. Any ideas?

mrricha
01-07-2012, 06:08 PM
Hey, thanks for answering Drivingzzz. That is very interesting about the ground plate i did not know that and I will remember that bit of info for future trouble shooting. I pulled the fuel line (just befor the fuel injector feed tube) and turned the key on and fuel gushed out so I know that the fuel pump is working. It seems like i'm getting fuel right up to the injectors
then nothing. I am fearful about messing with injectors the they look complicated and I don't know anything about them anyway. Any ideas? Anybody.

Tech II
01-07-2012, 10:29 PM
Well, if you have proper fuel pressure and it runs with carb cleaner being sprayed into the intake, then the injectors probably aren't being pulsed....disconnect an injector harness and attach a noid light.....it should flash when you crank the engine......if it doesn't, bad ICM, bad ECM/PCM, or bad wiring in between.......

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