PontiacBonnevilleClub.com

New member here, but I've been lurking around this site for about a week now.

Starting off by saying I just bought a 2000 SE. I bought it directly from the owner, in an "as is condition". Has 183k on the engine, knew just by looking that it needed new tie rods, a/c needed work, and check engine light was on. Also noticed previous owner had pulled apart the air cleaner assembly. He'd put a high performance air filter onto the original air intake hose, and it was the wrong size air filter to boot! There was no manner of stabilizing or securing the filter in place, so it was essentially wobbling around and hitting the PCM. The wire mesh on the filter tore through several of the wires to the PCM, and I automatically assumed this was the reason for the SES light.

Now, when I first pulled codes, here's what I got...

P0753 Shift Solenoid A Electrical
P0758 Shift Solenoid B Electrical
P0122 Throttle Position (TP) Sensor Circuit Intermittent Low Voltage
P1134 HO2S Transition Time Ratio Sensor 1
P1361 Ignition Control (IC) Circuit Low Voltage
P1362 Ignition Coil C Secondary Circuit Malfunction
P1404 IAT - B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance
and the temporary bane of my existence...
P1635 P1635 5 Volt Reference Circuit

The first thing I did was run out to the local pick and pull to grab a proper air cleaner assembly box and get rid of the high performance filter.
I started testing the 5 volt sensor wires on every sensor I could think of...I wasn't getting a voltage on anything...anywhere.
Next, I began my search for troubles. I dug through wire upon wire leading to the PCM, found any and all split, cracked, or broken wires, and started fixing them all.
After fixing wires, i started the car back up, let it run for about 10 minutes or so, turned it off, back on, and off again...I plugged my scanner back in, and everything was cleared EXCEPT for the dreaded 1635.

I started back at the beginning...I was checking parts along the way as I probed and poked around everywhere...
Started with sensors who had related codes above first....EGR was a bit dirty, happened to pick up a really good looking spare at the pick and pull for $10 just in case...cleaned existing one, and it cleaned up nicely...had to put on a new gasket, as old one was very frayed and split. EGR valve cleaned, I checked wires again...4.9V...on to next...

Ignition control sensor tested 4.8V, moving along...TP 5.0, MAP tested at 4.9V, MAF 5.0, A/C pressure sensor 4.9, IAT 4.9,
Fuel Tank sensor 4.9, ECT 5.0

code cleared on scanner..started car, shut off, started again, SES back on again...cannot figure out what is not connected or grounded to that 5V circuit.

I changed out the Upstream O2 Sensor because it was shot. Swapped out the IAT.

Have done a few other simple things like cleaning electrical connections and such.


If anyone has any other advice to toss this way...like I said, I'm stumped...have been checking and rechecking all day, and I'm at a loss as to what direction to go...

This should help: http://www.bonnevillesunlimited.com/P1635.pdf

Re-checking things today....
5 volt wire on TPS is flying all over the place...can't get a steady voltage
MAP sensor is staying a constant 4V
EGR is staying between 7.0 and 7.4V
most other sensors are staying between 4.6 and 5.2V

Also, oil pressure gauge on dash is staying low...sometimes causing "check gauges" light to go off and ding constantly.
Fuel pressure gauge is staying at above full constantly as well.

I'm assuming most of these issues are all caused by electrical issues...

Any other thoughts?

*still only pulling code 1635 as well

Think I'd check the oil pressure switch wire. Down by the switch.

Is the TPS voltage being measured with it connected? If so, what does it read with it disconnected? Is it steady, then?

Doing some more thorough checking, here's what' i've discovered...

TPS stays high (min of 7V) on 5V while connected, and no voltage at all when disconnected....swapped out TPS with a new one, and same thing...5V ground wire to PCM is one of the wires that was shredded by the previous owners performance air filter that was not attached properly.

Oil pressure sensor swapped out...oil pressure gauge on dash still sticking on 0.

On PCM itself, the 5V ground wire to Engine Oil pressure sensor, MAP sensor signal, MAP sensor ground, TPS sensor signal, and TPS 5v ground wires are the only wires that appear to be damaged from the air filter...


On that note, I had pretty much given up trying to fix these issues myself, as I didn't want to cause any further damage..

Also, at this point, I had temporarily twisted broken wires together, and taped them up to get a short term fix on the issue....car was starting up no problem, and running...very little driving with this car though (mostly to run 1/4 mile down the road to drop daughter off at daycare and back). I have stuck to riding the bus until I know these issues are fixed.

Now, I had a friend who is a mechanic come out to help me work on some things...he specializes in electrical wiring mostly...
He ripped apart my handy tape work (lol), and correctly spliced and soldered wires back together...did a continuity test to wires, and showed no issues...code P1635 cleared itself, and things seemed to be moving along...

In an attempt to test it out further, I ventured further from home and went 2 miles down the orad to the grocery store. When I was done, and went to leave, the car would not start.

The lights, wipers, radio, etc work fine. This happened late last night, and the Security light was staying on constant...Did the whole turn key to on position and wait 10 minutes, and try to start again...nothing. No click from starter or anything.

Went back out to look at it again today, and I can't figure out what the issue is...Could I have shorted out my PCM? does it need to be reset or something? Was soldering wires to PCM a bad idea? Yes, he soldered and used heat shrink wire covers.

Everything seems to be secure.
With key in "ON" position, and each individual part connected, I'm getting: 5.2V to TPS, 4.9 to MAP, 5.1 to oil pressure sensor, 4.8 to EGR, and most everything else I've tested is all within range.

With key in "ON" position, and each individual part disconnected, I'm getting: 4.9 to TPS, 4.9 to MAP, 5.0 to oil pressure, 4.9 to EGR, and everything else about the same...

Today, when I went back to test again, still no start, but the security light wasn't on. I disconnected battery, and ran to grab lunch, came back about 30 minutes later, reconnected battery and same thing..won't start.

At a loss once again...

problem has turned into stuff other than 1635 code issue, so I moved over to electric forum to scout out suggestions there

When you do you voltage measurements, do you use the vehicle as ground or the ground wire at each sensor? What are the voltage readings at the PCM for each sensor source?

had moved over to a different post...turns out I had a really bad battery...all replaced now, but car spent 5 days dead with driver window stuck down (before I realized I just needed the battery). Also, had a TON of rain over the weekend, and my list with all voltage readings I'd gotten from everywhere got soaked and is now un-readable...
Going out this afternoon to take measurements again...had done it both ways (vehicle as guard, AND ground wire).

At one point, I wasn't getting a voltage reading at the PCM for hardly anything...the more I'm looking into things, the more I'm thinking it's all somehow related to the PCM itself...

Will post again soon once I get measurements taken.

ok, so hoping i'm posting this so anyone can follow along...

tested the following, with engine in "ON" position, and grounded to the vehicle, and here's what I got:

Connected Disconnected
EGR: 3.83V 3.82V
MAF: 3.83V 3.83V
MAP: 35.64V (yes this is right!) 3.87V
TPS Wouldn't stop bouncing 3.81V
IAC 3.82V 3.83V
A/C sensor 3.84 3.81
oil pressure sensor 3.84 3.83

should I have checked any others? and I have not gotten to checking the PCM more thoroughly yet...obviously, there are issues pointing to TPS and MAP....

had to move my car...want to wait a bit for car to cool back down some before I continue...

also, why do you think I cannot get to 5V on anything?

for the record: I am trying to track down some place that can look at the car, without overcharging me....
(last place said $99.95, just to hook up their OBD reader, and diagnose...not even repair anything)
Funds are getting low, trying to conserve for parts vs. labor if possible

Just bought the car 3 weeks ago, and the inspection sticker is out, as is registration...I cannot renew registration without inspection...
and I cannot get it inspected with SES light on

Have a week left until I'm past the 30 days on my temp plates, and then late fees for title/reg start incurring as well.

Starting to think I got in over my head a little with this car, but I can say I DO prefer working on this Bonnie, rather than my old Grand Am! Had no room to work under that hood!

short video of trying to get a read on TPS...
http://www.youtube.com/watch?v=rrzbUX9k ... e=youtu.be

Let's see what you find when you check at the 5 volt sources.

Happy St. Patty's Day!
Was a hectic week, but I finally got around to testing more voltage today. Everything in above posts was still holding the same. Replaced the TPS, still same on 5V wire.
Testing every pin on PCM for every 5V source, I couldn't get any of them to read above 2.5 V....all grounds were between 0 and 0.2V.
Anything that should be 12V was between 11.9 and 12.30V.

Not sure if I have the most accurate pin layout for PCM as to which 5V wires are which. But, like I said, I tested every pin, and whatever the 5V pins all are, nothing was even close to 5V.
The pin diagram I have showed a few 5V wires that aren't in use on my PCM, and a few that are in use that show NOT in use on diagram, which is why I think I don't have a proper diagram for my 2000 SE...

Any thoughts?

This is what I have for the PCM connections.

Thanks Archon! That does not match with the pin diagram I have, and actually looks more like what my PCM pins match up to....busy all morning, but this afternoon/evening, i'll be taking a more in depth look at it.