TheLeftTomb707 Posted March 29, 2023 Share Posted March 29, 2023 (edited) I've been trying to get my 1990 Maui Blue Reatta registered in Arizona, but the engine light is on because of the throttle position sensor being too low. I've tried replacing it, but didn't work, I've tried replacing the actual connector because the clip was broke and I thought it wasn't making enough contact, but then the "too low" turned into "too high." I also can't clear codes because my diagnostic mode controls, by use the fan up and down, won't do anything so I can't clear them. I have also tried disconnecting the negative terminal on the battery for over 10 minutes, just to be sure, and that didn't do it. So, I don't know if the tps is still messed up or if it is still just showing the code. Your guy's help would be greatly appreciated. Update: I have tested the connector with a multimeter and is says 4.7v so I don't really know what that means in this scenario. Edited March 29, 2023 by TheLeftTomb707 (see edit history) Link to comment Share on other sites More sharing options...
2seater Posted March 29, 2023 Share Posted March 29, 2023 (edited) It sounds like you could have two separate issues. If all the controls on the Climate Control panel do not work, it probably needs to be cleaned. The contacts inside get dirty over time and cleaning the contacts almost always restores functionality. See here Reatta Owners Journal - How To Clean 1990 Climate Control Panel Use the diagnostic function to read the TPS voltage. ED01 is the TPS and it should read .38-.42 volts at idle position and over 4.0 volts at full throttle. Of course the Climate panel must be operational to use the onboard systems. Edit: Codes that are active will not clear and the TPS needs to be adjusted when it is being installed. Edited March 29, 2023 by 2seater (see edit history) Link to comment Share on other sites More sharing options...
padgett Posted March 29, 2023 Share Posted March 29, 2023 Have to wonder if the aftermarket display below has caused HVAC problems. The Reatta has a tightly integrated ALDL LAN. Once had a bad connector cause a TPS to fasil on a stop but read normal at rest. Found by logging parameters to a PC while driving. Link to comment Share on other sites More sharing options...
Ronnie Posted March 29, 2023 Share Posted March 29, 2023 14 hours ago, TheLeftTomb707 said: Update: I have tested the connector with a multimeter and is says 4.7v so I don't really know what that means in this scenario. If you are testing the connector with the key on between the black and gray wires you are probably reading the reference voltage supplied to the TPS by the ECM. Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted March 30, 2023 Author Share Posted March 30, 2023 (edited) @2seater Though the fan up and down work perfectly fine as regular climate control and I can't control the diagnostic mode to test the voltage if the controls don't work. @padgett I didn't think the aftermarket display mess with the HVAC since it's a 90 and doesn't have the oem touch screen. And I did already replace the tps connector if that is the connector your talking about. @Ronnie When I first start diagnosing today the middle signal wire read around 5v disconnected and I was "huh" so I start messing with the connector and then it read around 0.2v, I then connected it to the tps and used a paper clip to probe the connector and it read 5v again then I took it out still read 0.2v. So, I think the connector is a little wonky and the tps itself is bridging with the reference voltage somehow. Let me know what you think? Do you think I have to replace both of them again? Edited March 30, 2023 by TheLeftTomb707 (see edit history) Link to comment Share on other sites More sharing options...
Ronnie Posted March 30, 2023 Share Posted March 30, 2023 1 hour ago, TheLeftTomb707 said: When I first start diagnosing today the middle signal wire read around 5v disconnected and I was "huh" so I start messing with the connector and then it read around 0.2v, You're going to have figure out why your aren't getting a consistent reading. I believe the middle (dark blue) wire should have almost 0 volts with the connector unplugged. Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted March 30, 2023 Author Share Posted March 30, 2023 Yes, it reads 0.2v when unplugged but when I plug it into the sensor it reads almost 5v which, from what I've seen, it should read around 1v with it's fully closed. Link to comment Share on other sites More sharing options...
2seater Posted March 30, 2023 Share Posted March 30, 2023 7 minutes ago, TheLeftTomb707 said: Yes, it reads 0.2v when unplugged but when I plug it into the sensor it reads almost 5v which, from what I've seen, it should read around 1v with it's fully closed. It should be less than one volt when closed but if the arm on the sensor has not engaged the drive pin on the throttle shaft correctly, it may be stuck at full voltage? If I am understanding correctly, you can access the diagnostics, since it shows an ECM code in the above photo, but the fan control doesn't work to get beyond the Ec? point, correct? That means you cannot step through the various sensor data readings?? 1 Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted March 30, 2023 Author Share Posted March 30, 2023 yes, I can't except or deny the Ec? Link to comment Share on other sites More sharing options...
padgett Posted March 30, 2023 Share Posted March 30, 2023 I've gotten lost in this mess. Key on foot off the TPS center should read .38-.42v and "over 4.0v" at WOT Link to comment Share on other sites More sharing options...
2seater Posted March 30, 2023 Share Posted March 30, 2023 17 hours ago, TheLeftTomb707 said: yes, I can't except or deny the Ec? I cannot think of any reason your diagnostic system doesn't engage except the fan control button doesn't make good enough contact?? If that doesn't work, you are missing a lot of valuable and handy information. Maybe Padgett has a clue? Link to comment Share on other sites More sharing options...
2seater Posted March 31, 2023 Share Posted March 31, 2023 One other function that can't be accessed is the clear code function. Link to comment Share on other sites More sharing options...
Ronnie Posted March 31, 2023 Share Posted March 31, 2023 On 3/28/2023 at 9:17 PM, TheLeftTomb707 said: I also can't clear codes because my diagnostic mode controls, by use the fan up and down, won't do anything so I can't clear them. I have also tried disconnecting the negative terminal on the battery for over 10 minutes, just to be sure, and that didn't do it. Disconnecting the battery cable is probably clearing the code but the code might be coming back as soon as you turn the key on because the ECM senses the TPS is out of range. Link to comment Share on other sites More sharing options...
2seater Posted March 31, 2023 Share Posted March 31, 2023 Does the odometer reading work normally when not in diagnostics? That reading is a function of the BCM so ??? I was just looking at the photos again and I notice with the engine apparently running, the HVAC control panel is dark? It should be displaying something if ignition is on. Link to comment Share on other sites More sharing options...
2seater Posted March 31, 2023 Share Posted March 31, 2023 If the HVAC panel is blank, there is more diagnostic information missing. Information is located in the HVAC panel as well as the buttons to change function. Something is amiss in that area. Oil pressure doesn't look too healthy for almost 2k rpm but the pressure sender is a known problem item. Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted April 1, 2023 Author Share Posted April 1, 2023 11 hours ago, 2seater said: Does the odometer reading work normally when not in diagnostics? That reading is a function of the BCM so ??? I was just looking at the photos again and I notice with the engine apparently running, the HVAC control panel is dark? It should be displaying something if ignition is on. The odometer works normally and I have to have the engine running for it to go into diagnostic mode. Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted April 1, 2023 Author Share Posted April 1, 2023 8 hours ago, 2seater said: If the HVAC panel is blank, there is more diagnostic information missing. Information is located in the HVAC panel as well as the buttons to change function. Something is amiss in that area. Oil pressure doesn't look too healthy for almost 2k rpm but the pressure sender is a known problem item. the oil pressure suddenly dropped one day while idling. Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted April 1, 2023 Author Share Posted April 1, 2023 On 3/29/2023 at 8:01 PM, 2seater said: It should be less than one volt when closed but if the arm on the sensor has not engaged the drive pin on the throttle shaft correctly, it may be stuck at full voltage? If I am understanding correctly, you can access the diagnostics, since it shows an ECM code in the above photo, but the fan control doesn't work to get beyond the Ec? point, correct? That means you cannot step through the various sensor data readings?? correct, I'm really stuck between a rock and a hard place huh. Link to comment Share on other sites More sharing options...
padgett Posted April 1, 2023 Share Posted April 1, 2023 Well I'd start by R&Ring the HVAC control and cleaning the contacts but suspect when the LCD was installed the wiring got floogled. Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted April 1, 2023 Author Share Posted April 1, 2023 Does this look dirty enough to go threw it and clean it? Link to comment Share on other sites More sharing options...
2seater Posted April 1, 2023 Share Posted April 1, 2023 2 hours ago, TheLeftTomb707 said: The odometer works normally and I have to have the engine running for it to go into diagnostic mode. Something doesn't look right here. The engine should not need to be running to get into diagnostic mode, only key on. But that is beside the point, since it appears the engine was running with indicated oil pressure and rpm visible, and yet the HVAC panel was blank and dark? I don't have my car home to confirm exactly what it should look like at the moment before getting into the ECM sensor displays. Can anyone confirm?? Regarding the cleaning of the HVAC panel. The contacts are inside the little gray buttons. It is similar to cleaning phone button pads or remotes for tv's and such. Everything runs on very low voltages so it doesn't take much. The most common failure mode of the buttons is the ability to raise or lower temperature, but even if it doesn't cure the problem, it eliminates one possible cause. The diagnostic displays are a function of the BCM. Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted April 1, 2023 Author Share Posted April 1, 2023 I stand corrected, I'm testing stuff tonight and it actually went into diagnostic mode with just key on, the first time it's actually done it. Because before it would just flash the IPC and ECC for about 0.5 second and do nothing. 1 Link to comment Share on other sites More sharing options...
EmTee Posted April 1, 2023 Share Posted April 1, 2023 12 hours ago, TheLeftTomb707 said: the oil pressure suddenly dropped one day while idling. Bad oil pressure sender? Could a sensed loss of oil pressure make the ECU shut-off the fuel pump? Link to comment Share on other sites More sharing options...
padgett Posted April 1, 2023 Share Posted April 1, 2023 Relief valve stuck open will do the same thing but sender failure is more likely. Link to comment Share on other sites More sharing options...
2seater Posted April 1, 2023 Share Posted April 1, 2023 17 hours ago, TheLeftTomb707 said: I stand corrected, I'm testing stuff tonight and it actually went into diagnostic mode with just key on, the first time it's actually done it. Because before it would just flash the IPC and ECC for about 0.5 second and do nothing. Does it still fail to go past Ec? when you press Fan Up? You can read codes but not actual sensor data if that issue still exists. Link to comment Share on other sites More sharing options...
DS_Porter 89 Burgandy Posted April 2, 2023 Share Posted April 2, 2023 to EmTee's question - Yes if oil pressure drops low enough the Fuel Pump will drop out. Power to the fuel pump when the engine is running is supplied through NO contacts in the oil pressure sending unit. Years ago when I bought my first Reatta it was hard to start but when it finally did start after several seconds of cranking it ran perfectly. Power to the fuel pump runs through NO contacts in the fuel pump relay and separately through NO contacts in the oil pressure sending unit. When starting the engine the ignition is turned on and the ECM turns on the fuel pump for two seconds through the FuelPumpRelay located on the firewall. The fuel rail is pressurized and the engine starts and develops oil pressure. After two seconds the FuelPumpRelay is turned off and power runs through NO contacts in the oil pressure sending unit. 2 Link to comment Share on other sites More sharing options...
Ronnie Posted April 2, 2023 Share Posted April 2, 2023 My '88 model must have something wrong with it. I can unplug the oil pressure sensor/switch and my fuel pump will run to prime the system and shut off as it should after a few seconds. When I start the engine it runs just fine with the fuel pump powered by the fuel pump relay. I have tried it a couple of different times just to verify. I wish someone else would try unplugging their oil pressure sensor and report the results they get when they try to start the engine. Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted April 2, 2023 Author Share Posted April 2, 2023 On 4/1/2023 at 1:19 PM, 2seater said: Does it still fail to go past Ec? when you press Fan Up? Yes I still can't go past Ec? Link to comment Share on other sites More sharing options...
2seater Posted April 3, 2023 Share Posted April 3, 2023 5 hours ago, Ronnie said: My '88 model must have something wrong with it. I can unplug the oil pressure sensor/switch and my fuel pump will run to prime the system and shut off as it should after a few seconds. When I start the engine it runs just fine with the fuel pump powered by the fuel pump relay. I have tried it a couple of different times just to verify. I wish someone else would try unplugging their oil pressure sensor and report the results they get when they try to start the engine. The ECM energizes the fuel pump relay both for priming and for running. The prime we all know is to get enough fuel for the engine to start but when the ECM sees the pulsed signals from the ICM, it re-energizes the fuel pump relay. The switch in the oil pressure sender is a backup to the ECM control and connects directly to the fuel pump bypassing the relay. 2 Link to comment Share on other sites More sharing options...
2seater Posted April 3, 2023 Share Posted April 3, 2023 4 hours ago, TheLeftTomb707 said: Yes I still can't go past Ec? It would seem it is either the climate control or a BCM issue. The contacts in the climate panel is not uncommon but to stick part way into diagnostic is unusual. Link to comment Share on other sites More sharing options...
2seater Posted April 3, 2023 Share Posted April 3, 2023 What does the climate control screen look like in normal operation? Does it display fan speed, inside/outside temperature, air flow indicators etc..? Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted April 3, 2023 Author Share Posted April 3, 2023 It show's all other information normally. Link to comment Share on other sites More sharing options...
padgett Posted April 3, 2023 Share Posted April 3, 2023 When in HVAC mode can it change the fan speed ? Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted April 3, 2023 Author Share Posted April 3, 2023 Yes, without a problem. Link to comment Share on other sites More sharing options...
2seater Posted April 3, 2023 Share Posted April 3, 2023 In a perfect world, known good replacement modules would be on hand, BCM and Climate Control panel. Unless there is a wire or wires out of action, A head scratcher. Link to comment Share on other sites More sharing options...
Ronnie Posted April 3, 2023 Share Posted April 3, 2023 21 hours ago, TheLeftTomb707 said: Yes I still can't go past Ec? Have you ever been able to on this car? Or has this problem just recently started? Link to comment Share on other sites More sharing options...
TheLeftTomb707 Posted April 3, 2023 Author Share Posted April 3, 2023 This is my first time trying it since I got the car 6 months ago. Link to comment Share on other sites More sharing options...
2seater Posted April 3, 2023 Share Posted April 3, 2023 I read through the diagnostic section of the FSM looking for failure to enter diagnostics and both relevant pages indicate to replace the climate panel. These are quick photos from the 1990 FSM. The diagnostic tree under #3 indicates replace panel if diagnostics won’t engage and the text on the next page, Chart “C” indicates the panel should be replaced if it displays normal information but will not enter diagnostics proper. Link to comment Share on other sites More sharing options...
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