Mtrcr Posted September 28, 2019 Report Share Posted September 28, 2019 I recently purchase my first 720(bound to get more) it’s an 86 king cab st with the z24i 5spd 4x4. It is rev limited to about 3000 rpm. I posted in the Facebook page for 720s and was told it’s possibly the tps(or throttle sensor) but how do I go about checking this? I don’t have a fsm yet so I’m lost at the moment. 1 Quote Link to comment
datzenmike Posted September 28, 2019 Report Share Posted September 28, 2019 I thought it was limp home mode. All I have is the mid year '86 manual for the D21 Hardbody, but it did have the similar Z24i engine. It's usual for the ECU box under the driver's seat to store error codes and there is a procedure for displaying them but first the engine must be thoroughly warmed up first. The error codes are in the form of flashing Red and Green LEDs Count the Red flashes as 10s and Green flashes as units. For example 4 Red flashes followed by 4 Green would be error code 44 (which is " all self diagnostic items OK") I'll assume that you have the same thing so look on the box for the ON/OFF switch and be sure it is OFF before turning the ignition to OFF. To begin, shift to neutral, turn ignition to ON (not start)... Both Red and Green LEDs should light. Turn ECU box selector to ON be sure code 23 and 24 are displayed...2 Red 3 Green and 2 Red and 4 Green flashes repeat..... Depress gas pedal and release... Only code 24 should display Depress clutch shift from neutral to any gear, release clutch. Depress clutch shift back to neutral release clutch. ECU box should display code 44. If any other code(s) write them down. 11... CAS Crank angle sensor 12... Air flow meter 13... Water temp sender (not the one for the gauge) 21...Ignition signal 23... Idle switch 24... Neutral and clutch inhibitor switch 32... Start signal 42... Throttle sensor 43... Injector 44... Self diagnostic OK 1 Quote Link to comment
Mtrcr Posted September 28, 2019 Author Report Share Posted September 28, 2019 Limp in/limp home same thing just heard both from different manufacturers is all. But thank you very much for a place to start! 1 Quote Link to comment
datzenmike Posted September 28, 2019 Report Share Posted September 28, 2019 The limp mode is usually a forced over rich condition rather than a failure causing a severe lean condition which could damage the engine. On the outside the 720 and Hardbody Z24i engines are the same but we'll see. 1 Quote Link to comment
Mtrcr Posted September 28, 2019 Author Report Share Posted September 28, 2019 Yea I knew the over rich part but I didnt know how to start diag with these bc of my lack of knowledge on these particular trucks. 1 Quote Link to comment
datzenmike Posted September 28, 2019 Report Share Posted September 28, 2019 See if your Z24i has the diagnostic setting and down load the fault codes if there are any. 1 Quote Link to comment
Mtrcr Posted September 29, 2019 Author Report Share Posted September 29, 2019 I did it today. I got 11 and 43. 1 Quote Link to comment
Mtrcr Posted September 29, 2019 Author Report Share Posted September 29, 2019 The cas is in the dizzy correct? 1 Quote Link to comment
datzenmike Posted September 30, 2019 Report Share Posted September 30, 2019 Correct it is the dizzy. 43 is the injector(s) It says either of the two are not working from an electrical problem. As these codes could have been caused years ago and may even have been transient, and not erased, I would erase them and go for a drive. If they are valid they will store them again. To erase codes turn ignition ON, turn diagnostic mode selector to ON, and then turn to OFF. Take for a short drive and warm the engine then check for new stored code(s) 1 Quote Link to comment
Mtrcr Posted September 30, 2019 Author Report Share Posted September 30, 2019 I had the battery completely out of truck for 20+minutes one day tinkering with vacuum lines and other things. So unless the ecu can hold memory for that long I would think those codes are current troubles. Or am I wrong in that? Im going off previous experience with my Mazdas but every manufacturer is different. 1 Quote Link to comment
datzenmike Posted September 30, 2019 Report Share Posted September 30, 2019 No that works as well I believe. There is a procedure for testing the injectors. Got a volt meter? Want it? 1 Quote Link to comment
Mtrcr Posted September 30, 2019 Author Report Share Posted September 30, 2019 Yes sir I do and please! Is there a test procedure for the CAS as well? Quote Link to comment
datzenmike Posted October 1, 2019 Report Share Posted October 1, 2019 If under the seat it may be easier to remove it to get at. POWER CHECK Unplug the 15 pin connector and check the voltage between pin 101,102,103,104,114 and ground. You should read battery voltage (12.6v or w/e) GROUND CHECK On resistance scale check between pins 107, 112, 113 and ground. Should read zero resistance. See what you get 1 Quote Link to comment
Mtrcr Posted October 1, 2019 Author Report Share Posted October 1, 2019 This for just injectors or both injectors and CAS? Im assuming if batt volts and ohms are incorrect check wiring and plugs and if good replace as needed? Is the CAS a replaceable part or is it best just to get a whole new dizzy? 1 Quote Link to comment
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