Dickinson County Comanche Posted May 29, 2022 Author Share Posted May 29, 2022 Switched out known good relays from my 89. No change. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted May 30, 2022 Author Share Posted May 30, 2022 Took the computer out and probed from all power source pins to the O2 pin and haven’t gotten any ohms. Would this be a bad computer? Nothing looks burnt out or broken so I’m not entirely sure what it would be. Link to comment Share on other sites More sharing options...
eaglescout526 Posted May 30, 2022 Share Posted May 30, 2022 Yikes. I don't know how good you are with circuit boards but you could always open it up and take a look. This is could possibly the second ECU failure I’ve seen this month. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted May 30, 2022 Author Share Posted May 30, 2022 10 hours ago, eaglescout526 said: Yikes. I don't know how good you are with circuit boards but you could always open it up and take a look. This is could possibly the second ECU failure I’ve seen this month. Pin 35 is supposed to have 5V out at all times, correct? I have no voltage to pin 35 nor any continuity between any of the power or ground pins Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted May 30, 2022 Author Share Posted May 30, 2022 Just now, Dickinson County Comanche said: Pin 35 is supposed to have 5V out at all times, correct? I have no voltage to pin 35 nor any continuity between any of the power or ground pins As for poking through the board, I tested every one of the resistors I could and they all checked out fine in terms of ohms. None seemed to be blown out or bad. Link to comment Share on other sites More sharing options...
eaglescout526 Posted May 30, 2022 Share Posted May 30, 2022 Let me go find the 2.5L manual and see what it says for the O2->ECU Link to comment Share on other sites More sharing options...
eaglescout526 Posted May 30, 2022 Share Posted May 30, 2022 Pin 35 is O2 sensor input. You will not have any voltage there at all. Pin 1,2 are ground, Pin 10 is system ground. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted May 30, 2022 Author Share Posted May 30, 2022 1 hour ago, eaglescout526 said: Pin 35 is O2 sensor input. You will not have any voltage there at all. Pin 1,2 are ground, Pin 10 is system ground. So how does the O2 sensor get voltage back then? From the heater relay? Link to comment Share on other sites More sharing options...
eaglescout526 Posted May 30, 2022 Share Posted May 30, 2022 The only thing the O2 gets voltage is to the heater circuit. It sends its readings back to the ECU. If I recall I did a bench test of an O2 and I got readings from it heated up on the bench. So if the heater circuit is messed up and reads the mixture as not hot enough, it will richen the mixture to heat up the O2 until it is where it needs to be. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted May 30, 2022 Author Share Posted May 30, 2022 7 minutes ago, eaglescout526 said: The only thing the O2 gets voltage is to the heater circuit. It sends its readings back to the ECU. If I recall I did a bench test of an O2 and I got readings from it heated up on the bench. So if the heater circuit is messed up and reads the mixture as not hot enough, it will richen the mixture to heat up the O2 until it is where it needs to be. I’m not getting any voltage out of the O2 at all. The truck seems to run more lean than rich. I have a potentially good extra one laying around here so I’ll swap it in and see if that changes anything. Link to comment Share on other sites More sharing options...
eaglescout526 Posted May 30, 2022 Share Posted May 30, 2022 Give the O2 a shot. It could be dead if it hasnt ever been touched or replaced. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted June 3, 2022 Author Share Posted June 3, 2022 New O2 didn’t change anything. I have a friend with a snap-on brick and I ordered a plug so hopefully I can figure it out and stop trying to diagnose in the dark. Link to comment Share on other sites More sharing options...
eaglescout526 Posted June 4, 2022 Share Posted June 4, 2022 Yes this one has me stumped without really doing some digging and tearing apart the harness. Link to comment Share on other sites More sharing options...
gogmorgo Posted June 6, 2022 Share Posted June 6, 2022 Not reacting to throttle input would make me suspect the throttle position sensor. Once you get that brick hooked up take a look at the TPS value, see if it drops out for part of the sweep. You can also do this with a multimeter, but watching the % chance on the scan tool is more fun. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted July 8, 2022 Author Share Posted July 8, 2022 I solved it! It was simply just that the CPS (due to not having the pressed in inserts on the bellhousing) was just a little bit too far from the flex plate. A few light taps with a hammer and a long extension and it runs amazing now! The 2.5 with those 4.10s is pretty peppy, I’m quite surprised. Link to comment Share on other sites More sharing options...
eaglescout526 Posted July 8, 2022 Share Posted July 8, 2022 What?! That’s a wild thing to come across. Glad the problem has been solved! Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted July 11, 2022 Author Share Posted July 11, 2022 On 7/8/2022 at 11:32 AM, eaglescout526 said: What?! That’s a wild thing to come across. Glad the problem has been solved! I suppose that’s what happens when you swap a 2.8 auto to a 2.5. Link to comment Share on other sites More sharing options...
cruiser54 Posted July 11, 2022 Share Posted July 11, 2022 for future reference. CRUISER'S MOSTLY RENIX TIPS RENIX CPS TESTING AND ADJUSTING OCTOBER 30, 2015 SALAD 131 COMMENTS Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark. Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad. The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark. Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS itself as shown in Figure 2 as Connector A, crank the engine over. It won’t start with the CPS disconnected. You should get a reading of .5 AC volts. If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from NAPA or the dealer. Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off. A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8″ from the stock 5/16″, or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts. Another little tip to save tons of aggravation is to stick a bit of electrical tape to your 11mm socket and then shove the bolt in after it. This reduces the chances of dropping that special bolt into the bell housing. Revised 8/8/2016 Link to comment Share on other sites More sharing options...
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