95 Trooper, intermittant CEL & tranny troubles related?

[jeffc123]

I recently purchased a 95 Trooper LTD knowing it had a few issues. When checking the vehicle prior to purchase I noticed the check engine light (CEL) would come on intermittantly after 15-30 minutes of freeway driving. Also, the tranny fluid was really dirty and smelled very bad, but not burnt. This prompted me to pay close attention to the AT.

When the CEL comes on, I notice no difference in engine performance. When the engine is turned off for a few minutes then restarted, the CEL is off. I noticed the engine did idle a tiny bit rough at times. And rarely the idle speed would drop to the point of almost stalling when stopping after freeway driving.

The tranny does not shift as tight as it should when fully warm. Sometimes I feel like it is slipping a bit because engine rpm's go up when I hit the gas, but the speed does not increase as it should. And during 150 miles I drove it, I felt a slight shudder twice.

I planned on having the tranny rebuilt. But from reading the posts on this forum I see that dirty fluid, bad grounds, leaky intake manifold gaskets and possibly a dirty selector switch can tranny problems. So before spending the big bucks at the tranny shop, I thought I'd check out the other possibilities.

The first thing I did was flush the nasty tranny fluid. I understand some folks suggest not to do a complete flush on a tranny that has not been serviced in a long while. But I figured I was planning on rebuilding it anyway, so why not.

I wanted to change the filter too, but Oil Can Henery's didn't have the tools to remove the crossmember that supports the tranny. So they couldn't remove the pan. Yes, it does have a filter. According to the parts store, it's under a second internal pan and it costs $49.95.

After the flush I first thought the tranny problem was solved. It's shifts seemed tighter and smoother and there was more power. But after a few minutes in stop and go traffic the shifts started feeling weak again (almost weaker) and it still felt like the tranny was slipping at times.

It sounds strange but in some ways the tranny felt smoother and stronger but in some ways it seemed to slip more when shifting. So the complete flush did help in a way. But I'm not sure I would recommend anyone completely flushing a really dirty trans. I think you'd be taking a chance. Maybe replacing 1/4 of the total fluid every few hundred miles might work.

Before replacing the tranny filter, my next step was to find why the CEL is coming on. There might be something related to the tranny. I learned here on this forum that Autozone would read the codes for free. The problem is they don't have a code reader for pre-1996, ODB1 imports. At least not for my 95 Trooper.

The clerk at Autozone said it was fairly easy to check the codes without a code reader on these pre-1996 rigs. He didn't know "exactly" how, but he said one normally shorts or grounds a pin or two on the computer data port. Then the CEL would flash the codes in a morse code fashion.

I looked at his books and searched the web but I could find information showing exactly where the data port is or which pins to work with. One source said it was to the right of the accelerator pedal and I should jumper pin 1 and 3 together. Another source said it was under the left dash and I should jumper pin A and C together. I found no diagrams or photos.

Neither the Autozone clerk nor I could find what we felt was the data port. We found unhooked connectors but nothing that screamed "data port".

I need to know exactly which connector is the data port because I don't want to burn up the computer by using the wrong pins. Any help on locating the data port would be greatly appreciated. Maybe even give the color of the connector and a total of pins. Or a link to a photo would be nice. Anything.

Any suggestions on the tranny problem also would be appreciated.

Cheers,
Jeff


1995 Trooper LTD
AT, 3.2L, DOHC

[rodeo02]

Wheww.. hadda take a nap after reading this post! (j/kidding! )
You need to start by reading the OBD code(s) you have. Here is a link that will hopefully help: http://www.automotiveforums.com/vbul...ghlight=jumper

G/luck
Joel

[jeffc123]

rodeo02, Thanks for the link. I searched but did not find that one. Once I find the correct 3 way connector, I'm guessing I jumper the two outside ones, 1-3 or A-C. Correct?

Sorry about the initial long post. After reading a lot of posts on this forum, I felt most didn't have enough information. So I went the other way and apparently gave tooooooo much. I'll report what I find.

Cheers,
Jeff

[jeffc123]

Just got back from hunting for the data port. No loose 3 pin connectors on the right side of the gas pedal, under the dash. I'm guessing they should not be buried too deep.

The only loose 3 pin connectors I found were behind an access cover on the lower dash to lower the left of the steering wheel.

Behind the access cover there is an off white 3 pin, an orange 3 pin and a snow white 2 pin. The off white and orange 3 pin connectors go towards the computer. I can't see where they connect.

Could the off white 3 pin connector be the one ??

Cheers,
Jeff

[rodeo02]

Jeff you got me stumped ! Hopefully someone in the know will chime in! Try here: http://www.forum.planetisuzoo.com/ and over at 4x4wire.com as well.
G/luck
Joel

[jeffc123]

It's been a while so I thought it's time for an update....

I ended up going to a tranny repair shop for a checkup. They said it had two clutches burned out. I had it rebuilt and it works great now.

I went to the Isuzu dealer in town to check the CEL a few other things. They said the CEL was an EGR problem, code 032 I think. They wanted $400 to repair it. I said NO! They also said I needed new spark plugs and cables which should cure a small engine vibration.

I had a local mechanic clean the EGR port and replace the EGR valve, replace the spark plugs with NGK's. My trooper ran a bit better but the CEL still comes on after 20 or so minutes of freeway driving.

I then replaced the spark plug cables. The CEL still comes on but the engine vibration is much better, still there but better. When the CEL comes on and I come to a stop the CEL turns off, the engine doesn't hold a steady idle for maybe a minute, then smooths out. If I rev up to engine to 2000 rpms, the CEL comes on again and the engine will not hold at 2000 rpms but varies between 2000 and 2300 rpms.

Any suggestions on the CEL? Are there other EGR components other than the valve itself that needs replacing? I realize I should start a new threat on the CEL thing but I'll try here first.
Cheers,
Jeff

[cybrmartian]

I know this is an old post but did you ever find out why your CEL was coming on? Mine is doing the same thing. I have cleaned the EGR, Put in NGK plugs and replaced wires and everything else I could think of and my CEL only comes on after highway driving for an extended time and goes off when at idle then comes back on after 2000 RPM. I am lost on this.

Matt

[atfdmike]

This is in kick panel of LS (driver side) kick panel.

1995 Isuzu Truck Trooper (4 Door) V6-3165cc 3.2L SOHC (6VD1)

Vehicle Level Powertrain Management Computers and Control Systems Testing and Inspection Displaying & Reading Trouble Codes Without Scan Tool Without Scan ToolThe provision for communicating with the engine control module is the Data Link Connector. The data link connector is located behind the lower front instrument panel. It is used in the assembly plant to receive information in checking that the engine is operating properly before it leaves the plant. The diagnostic trouble code(s) stored in the engine control module's memory can be read either through a hand-held diagnostic scanner plugged into the data link connector or by counting the number of flashes of the "Check Engine" malfunction indicator lamp when the diagnostic test terminal of the data link connector is grounded.

Data Link Connector

The data link connector terminal "1" (diagnostic request) is pulled "Low" (grounded) by jumpering to data link connector terminal "3", which is a ground wire. This will signal the engine control module that you want to "flash" diagnostic trouble code(s), if any are present. Once terminals "1" and "3" have been connected, the ignition switch must be moved to the "ON" position, with the engine not running. At this point, the "Check Engine" malfunction indicator lamp should flash diagnostic trouble code 12 three times consecutively. This would be the following flash, sequence: "flash, pause, flash - flash, long pause, flash, pause, flash - flash, long pause, flash, pause, flash - flash". diagnostic trouble code 12 indicates that the engine control module's diagnostic system is operating. If diagnostic trouble code 12 is not indicated, a problem is present within the diagnostic system itself, and should be addressed by consulting the appropriate diagnostic chart.
Following the output of diagnostic trouble code 12, the "Check Engine" malfunction indicator lamp will indicate a diagnostic trouble code three times if a diagnostic trouble code is present, or it will simply continue to output diagnostic trouble code 12. If more than one diagnostic trouble code has been stored in the engine control module's memory, the diagnostic trouble code(s) will be output from the lowest to the highest, with each diagnostic trouble code being displayed three times.

[atfdmike]

Originally Posted by cybrmartian

I know this is an old post but did you ever find out why your CEL was coming on? Mine is doing the same thing. I have cleaned the EGR, Put in NGK plugs and replaced wires and everything else I could think of and my CEL only comes on after highway driving for an extended time and goes off when at idle then comes back on after 2000 RPM. I am lost on this.

Matt

Using the info about reading the codes, if your light is illuminating, then a code should be stored even if the light turns off. Read it and let us know. Code 32 is egr related, and usually cleaning carefully helps unless something else is wrong. If you get a different code, post it and we can look for answers.