1987 JEEP : TPS Question

FYI
The Bendix Jeep Tester will get you those codes on an '87 and on my '88.
I have the manual with all of the codes.
I sent those codes to the Renix group on Yahoo after scanning them
http://autos.groups.yahoo.com/group/RENIXPower
but I don't think that they were grouped & posted in a file yet.

The Tester also allows you to see what the ECM sees, TPS position, CTS
temperature, etc.
--
later,
dave AKA vwdoc1
88 XJ 4.0 auto


"Jeff Strickland" > wrote in message
...
>
> "PeterD" > wrote in message

snip

>> When you put a scan tool on it, what DTCs do you get?
>
>
> It's an '87, not '97. There is no scan tool to pull DTCs.

Or, you can cycle the key OFF/ON five times and the Check light will blink
the codes.




"dave AKA vwdoc1" > wrote in message
...
> FYI
> The Bendix Jeep Tester will get you those codes on an '87 and on my '88.
> I have the manual with all of the codes.
> I sent those codes to the Renix group on Yahoo after scanning them
> http://autos.groups.yahoo.com/group/RENIXPower
> but I don't think that they were grouped & posted in a file yet.
>
> The Tester also allows you to see what the ECM sees, TPS position, CTS
> temperature, etc.
> --
> later,
> dave AKA vwdoc1
> 88 XJ 4.0 auto
>
>
> "Jeff Strickland" > wrote in message
> ...
>>
>> "PeterD" > wrote in message
>
> snip
>
>>> When you put a scan tool on it, what DTCs do you get?
>>
>>
>> It's an '87, not '97. There is no scan tool to pull DTCs.
>
>

Not on the Renix system AFAIK.
I think the 1991-1995 "Chrysler" OBD-I might have the blinking system. ;-)


"Jeff Strickland" > wrote in message
...
> Or, you can cycle the key OFF/ON five times and the Check light will blink
> the codes.
>
>
>
>
> "dave AKA vwdoc1" > wrote in message
> ...
>> FYI
>> The Bendix Jeep Tester will get you those codes on an '87 and on my '88.
>> I have the manual with all of the codes.
>> I sent those codes to the Renix group on Yahoo after scanning them
>> http://autos.groups.yahoo.com/group/RENIXPower
>> but I don't think that they were grouped & posted in a file yet.
>>
>> The Tester also allows you to see what the ECM sees, TPS position, CTS
>> temperature, etc.
>> --
>> later,
>> dave AKA vwdoc1
>> 88 XJ 4.0 auto
>>
>>
>> "Jeff Strickland" > wrote in message
>> ...
>>>
>>> "PeterD" > wrote in message
>>
>> snip
>>
>>>> When you put a scan tool on it, what DTCs do you get?
>>>
>>>
>>> It's an '87, not '97. There is no scan tool to pull DTCs.
>>
>>
>
>

The Renix ECU doesn't store DTCs. The tester you refer to (MS 1700)
will guide you through a self test (key on, key off, step on
accelerator, etc) and look for the proper response. If it doesn't see
what it expects, it'll give you a code to look up a diagnostic
procedure. Useful if you have a dead sensor, but no help if your
problem is intermittent or a sensor that's just slightly off. The most
useful thing is the serial data readout which lets you see sensor
values in real time, but only one sensor at a time.

This tool was replaced by the Jeep/Eagle adapter used with the DRBII.



On Thu, 29 Oct 2009 21:38:44 -0500, "dave AKA vwdoc1"
> wrote:

>FYI
>The Bendix Jeep Tester will get you those codes on an '87 and on my '88.
>I have the manual with all of the codes.
>I sent those codes to the Renix group on Yahoo after scanning them
>http://autos.groups.yahoo.com/group/RENIXPower
>but I don't think that they were grouped & posted in a file yet.
>
>The Tester also allows you to see what the ECM sees, TPS position, CTS
>temperature, etc.

That serial stream is what I'm really most interested in. Any suggestions
on where to find out the specifics of the interface? I fiddled with it and
got the stream to display from a serial port connected via an optical
isolator (I don't trust anyone's implementation!) - can't recall all the
details, but it was pretty straight forward to that point. Of course, I
had no idea of what it meant but I could get a predictable stream. The
interpretation and control codes are what I'm looking for.

bllsht wrote:

> The Renix ECU doesn't store DTCs. The tester you refer to (MS 1700)
> will guide you through a self test (key on, key off, step on
> accelerator, etc) and look for the proper response. If it doesn't see
> what it expects, it'll give you a code to look up a diagnostic
> procedure. Useful if you have a dead sensor, but no help if your
> problem is intermittent or a sensor that's just slightly off. The most
> useful thing is the serial data readout which lets you see sensor
> values in real time, but only one sensor at a time.
>
> This tool was replaced by the Jeep/Eagle adapter used with the DRBII.
>
>
>
> On Thu, 29 Oct 2009 21:38:44 -0500, "dave AKA vwdoc1"
> > wrote:
>
>>FYI
>>The Bendix Jeep Tester will get you those codes on an '87 and on my '88.
>>I have the manual with all of the codes.
>>I sent those codes to the Renix group on Yahoo after scanning them
>>http://autos.groups.yahoo.com/group/RENIXPower
>>but I don't think that they were grouped & posted in a file yet.
>>
>>The Tester also allows you to see what the ECM sees, TPS position, CTS
>>temperature, etc.

--
Will Honea

Since 10/2009, just wanted to follow up and update on the TPS issue.

I was sure my transmission was an electrical issue, and not a mechanical
one. The TPS seemed to be a part of that premise. In the summer 0f 2010,
after driving without overdrive for a year, I pulled into a sleeply
little town in Mississippi (Pascagoula) and a home grown auto repair
shop. Ole boy said his modis scanner said my brake was depresssed. ---
Overdrive solved by replacing a burnt wire under dash near pedals. Just
saved $2,300 for what 10 authorized mechanics wanted to charge.

Well, it's winter time again and my jeep is following it's attitude as
in the past 5 winters. Cold temperature (35 to 45 degrees) it reeves
over 3500 rpms the first time starting it in the morning. I have to shut
off, and restart no less than 4 times before the reeving of the engine
subsides. Any suggestions? EGR? vacuum? relay?

Your input has been and is appreciated,
Ken


On 10/27/2009 9:39 AM, wrote:
> Bill Hughes, Will, & Bllsht,
>
> Thank each of you for responding.
>
> When I posted the message, I decided to jump into the jeep and go
> purchase a new TPS as a last ditch effort when I considered the other
> possible costs.
>
> My initial symptoms started ALL at once, back in May this year. While
> driving on the interstate, the transmission when out (save 1st gear &
> some second). Low fluid. So I immediately added enough fluid to get home.
>
> The transmission wouldn't work properly and also started having engine
> idle problems (cold start kills, and also at running temperature having
> very high idles).
>
> I dropped the pan, changed the screen, cleaned the magnet (slight haze
> covering it, no shavings), and the bottom of the pan was absolutely free
> of debris. The fluid smelled new and clear (zero burn scent). I put on a
> new screen and replaced the fluid, adding some lucas as a kicker.
>
> I brought it into several shops and they would only tell me "oh, about
> two thousand dollars", but yet I'd hit a bump and I'd have 4 gears back
> up shifting and down shifting normally as if I never had a problem (but
> the idle problem prevailed).
>
> Each time the transmission would randomly go ignorant, I'd checked the
> TPS. Each time it reported in @ 83ish% --until September. Once I
> replaced the TPS and calibrated, the idle issue when away -- and so did
> the transmission issue (save one). I did not get overdrive back. It's
> been a month, and I am at another dead end on what direction I should take.
>
> I do not know if I damaged the 4th gear/overdrive planetary when I ran
> low on fluid (temperature wise) back in May, or if I have a pending
> overdrive electronic issue? MT2500 didn't shed any usable clues.
>
> Based upon each of your previous postings with advise, I am going to
> break open & look into the wiring harness and also disconnect at the
> bulkhead to check the contacts this weekend.
>
> Do you think my neutral safety switch is over due at 270k miles?
> --Percentage wise? Aisin Warner 30-40LE.
>
> Any Suggestions?
> Thanks,
> Ken
>
>
>
> Will Honea wrote:
>> wrote:
>>
>>> 1987 JEEP CHEROKEE CHIEF, 4Door,4WD, 6 cyl 4.0L Automatic
>>> VIN# xJCMRxxxxHTxxxxxx with a RENIX ECU.
>>>
>>> Where does the Throttle Position Sensor input voltage come from?
>>>
>>> I replaced the TPS 2 years ago and calibrated the OUT divided by the IN
>>> @ 83%, and it worked well until recently.
>>>
>>> My current TPS readings are IN = 7.81 vdc, and OUT = 5.65 vdc.
>>>
>>> I am suspecting my problems are centered in the origin of the voltage
>>> being supplied too high to the TPS and not the TPS itself.
>>>
>>> Any advice is welcomed, thanks.
>>
>> The factory manual for the Renix system (same as my '88 Commanche)
>> says that
>> the reference voltage should be 5.0 volts supplied by the computer but
>> yours may be running slightly differently. My adjustment procedure (from
>> the manual) is .86 volts ouput with the throttle at dead idle to 4.95 at
>> WOT. If it is the 5.0 reference, you'll also find that the MAP sensor
>> supply is high. If that's the case, good luck finding another
>> computer! As I recall, the Rennix system was only used in 87 and 88 -
>> maybe a few of
>> early the 89's had it butthe 90's on used the MOPAR unit. That had
>> totally
>> different sensors and was set up for the HO engine with different intake
>> manifolds and headers along with a reworked head. If the engine runs OK
>> beyond the idle/WOT performance, you might be able to repair the voltage
>> reference inside the computer but that's chancy - I've never gotten the
>> schematics for that beast.
>>

Do you have insight as to why the engine would reeve up in conditions of
cool weather - clod starts?
Thanks,
Ken

On 10/28/2009 1:32 PM, PeterD wrote:
> On Tue, 27 Oct 2009 09:39:55 -0600, wrote:
>
>> Bill Hughes, Will,& Bllsht,
>>
>> Thank each of you for responding.
>>
>> When I posted the message, I decided to jump into the jeep and go
>> purchase a new TPS as a last ditch effort when I considered the other
>> possible costs.
>>
>> My initial symptoms started ALL at once, back in May this year. While
>> driving on the interstate, the transmission when out (save 1st gear&
>> some second). Low fluid. So I immediately added enough fluid to get home.
>>
>> The transmission wouldn't work properly and also started having engine
>> idle problems (cold start kills, and also at running temperature having
>> very high idles).
>>
>> I dropped the pan, changed the screen, cleaned the magnet (slight haze
>> covering it, no shavings), and the bottom of the pan was absolutely free
>> of debris. The fluid smelled new and clear (zero burn scent). I put on a
>> new screen and replaced the fluid, adding some lucas as a kicker.
>>
>> I brought it into several shops and they would only tell me "oh, about
>> two thousand dollars", but yet I'd hit a bump and I'd have 4 gears back
>> up shifting and down shifting normally as if I never had a problem (but
>> the idle problem prevailed).
>>
>> Each time the transmission would randomly go ignorant, I'd checked the
>> TPS. Each time it reported in @ 83ish% --until September. Once I
>> replaced the TPS and calibrated, the idle issue when away -- and so did
>> the transmission issue (save one). I did not get overdrive back. It's
>> been a month, and I am at another dead end on what direction I should take.
>>
>> I do not know if I damaged the 4th gear/overdrive planetary when I ran
>> low on fluid (temperature wise) back in May, or if I have a pending
>> overdrive electronic issue? MT2500 didn't shed any usable clues.
>>
>> Based upon each of your previous postings with advise, I am going to
>> break open& look into the wiring harness and also disconnect at the
>> bulkhead to check the contacts this weekend.
>>
>> Do you think my neutral safety switch is over due at 270k miles?
>> --Percentage wise? Aisin Warner 30-40LE.
>
> When you put a scan tool on it, what DTCs do you get?

wrote:

> Since 10/2009, just wanted to follow up and update on the TPS issue.
>
> I was sure my transmission was an electrical issue, and not a mechanical
> one. The TPS seemed to be a part of that premise. In the summer 0f 2010,
> after driving without overdrive for a year, I pulled into a sleeply
> little town in Mississippi (Pascagoula) and a home grown auto repair
> shop. Ole boy said his modis scanner said my brake was depresssed. ---
> Overdrive solved by replacing a burnt wire under dash near pedals. Just
> saved $2,300 for what 10 authorized mechanics wanted to charge.
>
> Well, it's winter time again and my jeep is following it's attitude as
> in the past 5 winters. Cold temperature (35 to 45 degrees) it reeves
> over 3500 rpms the first time starting it in the morning. I have to shut
> off, and restart no less than 4 times before the reeving of the engine
> subsides. Any suggestions? EGR? vacuum? relay?
>
> Your input has been and is appreciated,

My wife showed me how to fix that on a 4.0L I6: KEEP YOUR FOOT OFF THE GAS.

More specifically, the old MJ (Renix system) does this race thing on cool
starts ("cold" around here is generally single digits, +-, and with those
the darned thing starts fine). At those intermediate temps, it will race as
you describe under two conditions: If I give it ANY gas while starting and
(oddly enough) if I pull into the drive in 2nd or 3rd then turn the engine
off without letting it idle for a second or two. The second one there acts
like a restart after stalling the engine taking off from a stop and backs
off pretty quick but I can't figure why it "remembers" a stall overnight.

Two things helped the first of the above two: 1. clean the TPS lug really
well and 2. get some contact cleaner into the TPS itself then work it back
and forth to get the corrosion off.

--
Will Honea