95 Bonneville 3.8l vin.K wont start

[Tonedog]

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]

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]

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]

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]

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]

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]

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 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]

Originally Posted by Tonedog

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

[Tonedog]

Thanks again, I found this site from a google search, I didnt realize this site had so much info.

[Tonedog]

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]

Are you absolutely sure the tab on the TPS is in the correct position?

[Tonedog]

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]

Originally Posted by Tonedog

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

I 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! 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.

[Tonedog]

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]

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!